Planarity of benzoyldithiocarbazate tuberculostatics. II. Diesters of benzoyldithiocarbazic acid

The emergence of drug‐resistant strains of Mycobacterium tuberculosis has intensified efforts to identify new lead tuberculostatics. Our earlier studies concluded that the planarity of a molecule correlates well with its tuberculostatic activity. According to our hypothesis, only derivatives whose molecules are capable of adopting a planar conformation may show tuberculostatic activity. The structures of three new potentially tuberculostatic compounds, namely N′‐[bis(methylsulfanyl)methylidene]‐N‐methyl‐4‐nitrobenzohydrazide (denoted G1), C₁₁H₁₃N₃O₃S₂, N′‐[bis(benzylsulfanyl)methylidene]‐N‐methyl‐4‐nitrobenzohydrazide (denoted G2), C₂₃H₂₁N₃O₃S₂, and N′‐[(benzylsulfanyl)(methylsulfanyl)methylidene]‐4‐nitrobenzohydrazide (denoted G3), C₁₆H₁₅N₃O₃S₂, were determined by X‐ray diffraction. The significant distortion from planarity caused by the methyl substituent at the N atom of the hydrazide group or the NO₂ substituent in the aromatic ring leads to the loss of tuberculostatic activity for G1, G2 and G4 {systematic name: N′‐[bis(methylsulfanyl)methylidene]‐2‐nitrobenzohydrazide}. A similar effect is observed when there are large substituents at the S atoms (G2 and G3).     

Metallcarbonyl-Synthesen. 23. Kristallstruktur und Reaktionsverhalten von Carbonylmetall-Komplexen des Heptamethylindens

Syntheses of Metal Carbonyls. 23. Crystal Structure and Reactivity of Heptamethylindenyl Carbonyl Metal Complexes Reaction of heptamethylindene (C₉(CH₃)₇, 1 ) with Re₂(CO)₁₀ yields [η⁵-C₉(CH₃)₇]Re(CO)₃ ( 2 ), which reacts with NO⁺BF₄^? to form the cationic complex [{η⁵-C₉(CH₃)₇}Re(CO)₂NO]⁺BF₄^? ( 3 ). Irradiation of 2 with UV light in the presence of triethyl phosphite leads to formation of [η⁵-C₉(CH₃)₇]Re(CO)₂[P(OC₂H₅)₃] ( 4 ). Alkylation of (CH₃)₃SnCl with Ind*Li gives [η¹-C₉(CH₃)₇]Sn(CH₃)₃ ( 5 ). All compounds were characterized by spectroscopic methods. The molecular structures of 3 and 5 were determined by single crystal X-ray diffraction ( 3 : P2₁/n (14), a = 1497.7(4) pm, b = 879.0(2) pm, c = 1609.0(4) pm and β = 110.99(2)°, R₁ = 0.038, wR₂ = 0.080; 5 : P2₁/n (14), a = 726.1(1) pm, b = 2930.7(3) pm, c = 930.0(1) pm and β = 112.834(5)°, R₁ = 0.044, R_w = 0.048). Complexes 2 ? 4 exhibit a piano stool configuration with a η⁵-coordinated permethylindenyl ligand (Ind*). Compound 5 displays a η¹ -coordination of the Ind* ligand. Temperature enhancement causes a hapticity change, as observed by NMR spectroscopy.     

31P-NMR. Measurements on Palladium-Phosphine Complexes. Nuclear overhauser effects and spin-lattice relaxation times

The ³¹P{¹H} nuclear Overhauser effects (NOE's) and ³¹P-spin-lattice relaxation times (T₁) for a series of trans-[PdCl₂P₂], P ? PEt₃, PPr₃ⁿ, PBu₃ⁿ, PMe₂Ph, PMePh₂, P(p-Tol)₃, P(cyclohexyl)₃ complexes are reported. Both the NOE and T₁ values depend upon the choice of solvent. The dipole-dipole mechanism dominates the spin-lattice relaxation of the coordinated phosphorus atom with the T₁ values for the PEt₃, PPr₃ⁿ, and P (cyclohexyl)₃ complexes decreasing with increasing molecular weight of the phosphine.     

The phenomenon of conglomerate crystallization. XIX. Clavic dissymmetry in coordination compounds. XVII

[Co(NH₃)₄(oxalato)]NO₃·H₂O (1) crystallizes as a conglomerate in space groupP2₁2₁2₁ with unit cell constants ofa=7.944(3),b=9.904(11), andc=12.700(2) Å;V=999.15 ų;d(calc.;z=4)=1.968 g cm^–3. [Co(NH₃)₄(oxalato)]¦·H₂O (2) crystallizes in space groupP2₂/n with cell constants ofa=7.285(1),b=9.959(3),c=15.410(5) Å;=102.63(2)° andV=1090.98 ų; d(calc;z=4) = 2.192 g cm^–3. Data were collected over the ranges of 4°270° and 4°255°, respectively for compounds1 and2. This resulted in a total of 2515 and 2823 data for the solution and refinement of the structures of compounds1 and2, respectively. When the refinements converged, the finalR(F) andR _w (F) values were, respectively, 0.073 and 0.080 for1 and 0.0378 and 0.0353 for2.Since neither data set was sufficiently good to give a sensible set of positions for all of the hydrogens, the stereochemistry of the two cations could only be defined by the positions of the heavy atoms. In the absence of reliable amine hydrogen positions, N(amine)-O(nitrate and oxalate) distances were examined. Close N(amine)-O(nitrate and oxalate) contacts indicate the presence of a network of significant hydrogen bonds in1. The N-O distances for compound2 also show the presence of hydrogen bonding between the amines and the oxalate ligand and water; however, the bonds are not of the same magnitude as the interactions involving the nitrate oxygens in1. Despite the similarity between the cations of1 and2, the Co-N distances in the two do not exhibit the same pattern. In1, the Co-N distances for amines trans to one another are shorter than the Co-N distances for amines trans to oxalate oxygens; this effect is reversed in2.     

Fluordiazadiphosphetidine, 17. Mitt.

The reactions of (CH₃NPF₃)₂ and F₃P(CH₃N)₂PF₂OCH₃ with lithium-1,1,1-trimethyl-N-(trimethylsilyl)-silanamide yield two new dispiro-compounds:XF₂P(CH₃N)₂PF(NSiCH₃)₂PF(CH₃N)₂PF₂ X withX=F, OCH₃. Synthesis, mass-spectra and X-ray structures are discussed.

Herrn Prof. Dr.K. L. Komarek zum 60. Geburtstag gewidmet.     

The phenomenon of conglomerate crystallization. XVIII. Clavic dissymmetry in coordination compounds. XVI

The x-ray crystal structure of {[Co(NH₃)₄(CO₃)]NO₃}₂ · H₂O has been determined as part of a study of the intra- and interionic interactions present in crystals of several transition-metal-amine complexes chosen to examine the occurrence and causes of conglomerate crystallization. {[Co(NH₃)₄(CO₃)]NO₃}₂ · H₂O crystallizes in the monoclinic space group P2₁/n with cell constantsa=7.4960(9)Å,b=22.673(6),c=10.513(1), and=91.41(1)°;V=1786.12 ų, andd(calc;Z=4)=1.915 g cm^–3. In all, 5333 data were collected over the range of 4° 2 60°; of these, 3395 [independent and with /3(1)] were used in the structural analysis. Data were corrected for absorption (=19.361 cm^–1) and the relative transmission coefficients ranged from 0.9987 to 0.8013. The data were of a quality such that both ammonia and water hydrogens were found in difference Fourier maps. The finalR(F) andR _w(F) residuals were, respectively, 0.0333 and 0.0332. A trans effect is observed for both cations of {[Co(NH₃ (CO₃)]NO₃}₂ · H₂O. The equatorial nitrogens, trans to the carbonato oxygens, have shorter Co-N distances than the axial nitrogens, trans to one another. The carbonato ligands are not symmetrically bonded to their respective metal centers. The Co-O distances for cation 1 are 1.913(1) and 1.903(1) Å and those for cation 2 are 1.916(1) and 1.896(1) Å. The structure reveals the existence of an intricate array of hydrogen bonds, involving both the chelating and nonchelating oxygens of the carbonato ligands as hydrogen bond acceptors of the amine hydrogens. The amine hydrogens are also involved in significant hydrogen-bonding interactions with the nitrate oxygens and water of crystallization, although they are generally weaker than those of the carbonato oxygens.     

Glycosylidene Carbenes. Part 6. Synthesis of alkyl and fluoroalkyl glycosides

The syntheses of glycosides from the diazirine 1 and a range of alcohols under thermal and/or photolytic conditions are described. Yields and diastereoselectivities depend upon the pK_HA values of the alcohols, the solvent, and the reaction temperature. The glycosidation of weakly acidic alcohols (MeOH, EtOH, i-PrOH, and t-BuOH, 1 equiv. each) in CH₂Cl₂ at room temperature leads to the glycosides 2–5 in yields between 60 and 34% (Scheme 1 and Table 1). At ?70 to ?60°, yields are markedly higher. In CH₂Cl₂, diastereoselectivities are very low. In THF, at ?70 to ?60°, however, glycosidation of i-PrOH leads to α-D -/β-D - 4 in a ratio of 8:92. More strongly acidic alcohols, such as CF₃CH₂OH, (CF₃)₂ CHOH, and (CF₃)₂C(Me)OH, and the highly fluorinated long-chain alcohols CF₃(CF₂)₅(CH₂)₂OH ( 11 ) and CHF₂(CF₂)₉CH₂OH ( 13 ) react (CH₂Cl₂, r.t.) in yields between 73 and 85% and lead mainly to the β-D -glucosides β-D - 6 to β-D - 8 , β-D - 12 , and β-D - 14 (d.e. 14–68%). Yields and diastereoselectivities are markedly improved, when toluene, dioxane, 1,2-dimetoxyethane, or THF are used, as examined for the glycosidation of (CF₃)₂C(Me)OH, yielding (1,2-dimethoxyethane, 25°) 80% of α-D -/ β-D - 8 in a ratio of 2:98 (d.e. 96%; Table 4). In EtCN, (CF₃)₂C(Me)OH yields up to 55% of the imidate 10 . Glycosidation of di-O-isopropylideneglucose 15 leads to 16 (CH₂Cl₂, r.t.; 65%, α-D / β-D = 33:67). That glycosidation occurs by initial protonation of the intermediate glycosylidene carbene is evidenced, for strongly acidic alcohols, by the formation of 10 , derived from the attack of (CF₃)₂MeCO^? on an intermediate nitrilium ion (Scheme 4), and for weakly acidic alcohols, by the formation of α-D - 9 and β-D - 9 , derived by attack of i-PrO^? on intermediate tetrahydrofuranylium ions. A working hypothesis is presented (Scheme 3). The diastereoselectivities are rationalized on the basis of a protonation in the σ plane of the intermediate carbene, the stabilization of the thereby generated ion pair by interaction with the BnO? C(2) group, with the solvent, and/or with the alcohol, and the final nucleophilic attack by RO^? in the π plane of the (solvated) oxonium ion.     

The gas-phase decomposition of methylsilane. Part III. Kinetics

The homogeneous gas-phase decomposition kinetics of methylsilane and methylsilane-d₃ have been investigated by the comparative-rate-single-pulse shock-tube technique at total pressures of 4700 torr in the 1125–1250 K temperature range. Three primary processes occur: CH₃SiH₃ → CH₃SiH + H₂ (1), CH₃SiH₃ → CH₄ + SiH₂ (2), and CH₃SiH₃ → CH₂ = SiH₂ + H₂ (3). The high-pressure rate constants for the primary processes in CH₃SiH₃ obtained by RRKM calculations are log (k₁ + k₃) (s^?1) = 15.2 - 64,780 Cal/θ and log k₂ (s^?) = 14.50 - 67,600 → 2800 Cal/θ. For CH₃SiD₃ these same rate constants are log k₁ (s^?) = 14.99 - 64,700 cal/θ log k₂ (s^?) = 14.68 – 66,700 → 2000 cal/θ, and log k₃ (s^?) = 14.3 ? 64,700 cal/θ.     

Azole. 45.

The three title compounds, namely (Z)‐1‐(4,5‐di­nitro­imidazol‐1‐yl)‐3‐morpholinopropan‐2‐one 2,4‐di­nitro­phenyl­hydrazone, C₁₆H₁₇N₉O₉, (IV), (Z)‐3‐morpholino‐1‐(4‐morpholino‐5‐nitro­imidazol‐1‐yl)propan‐2‐one 2,4‐di­nitro­phenyl­hydrazone, C₂₀H₂₅N₉O₈, (Va), and (E)‐3‐morpholino‐1‐(4‐morpholino‐5‐nitro­imidazol‐1‐yl)propan‐2‐one 2,4‐di­nitro­phenylhydra­zone tetra­hydro­furan solvate, C₂₀H₂₅N₉O₈·C₄H₈O, (Vb), have been prepared and their structures determined. In (IV), the C‐4 nitro group is nearly perpendicular to the imidazole ring and the C‐4—NO₂ bond length is comparable to the value for a normal single Csp²—NO₂ bond. In (IV), (Va) and (Vb), the C‐­5 nitro group deviates insignificantly from the imidazole plane and the C‐5—NO₂ bond length is far shorter in all three compounds than C‐4—NO₂ in (IV). In consequence, the C‐4 nitro group in (IV) is easily replaced by morpholine, while the C‐5 nitro group in (IV), (Va) and (Vb) shows an extraordinary stability on treatment with the amine. The E configuration in (Vb) is stabilized by a three‐centre hydrogen bond.     

Front Cover: Water-Solvation-Dependent Spin Transitions in Cobalt(II)-Octacyanidometallate Complexes (Eur. J. Inorg. Chem. 30/2023)

The spin-crossover (SCO) and charge-transfer (CT) phenomena, the switching processes between two distinguishable magnetic states, are promising for developing materials capable of sophisticated memory and sensing functionalities. The majority of SCO systems are based on iron(II) complexes. However, cobalt(II)-2,2′:6′,2′′-terpyridine (terpy) systems emerge as a promising alternative. In this work, new complex salts [Co^II(terpy)₂]₂[Mo^IV(CN)₈] ⋅ 15H₂O, Co₂Mo (H₂O), and [Co^II(terpy)₂]₃[W^V(CN)₈]₂ ⋅ 12H₂O, Co₃W₂ (H₂O) were synthesized and physiochemically characterized. Structural studies for both compounds revealed [Co(terpy)₂]²⁺ layers pillared by octacyanidometallate anions and completed with water molecules between them. Magnetic studies confirmed that the (de)solvated phases of both complexes exhibit partial SCO on the cobalt(II) centers: Co^II−LS (S_Co(II)-LS=¹/₂)↔Co^II−HS (S_Co(II)-HS=³/₂). Moreover, handling dehydrated samples in a high-humidity environment leads to partial recovery of previous magnetic properties via humidity-induced SCO for Co₂Mo : Co^II−HS→Co^II−LS, and the new phenomenon of isothermal humidity-activated charge-transfer-induced spin transition, which we define here as HACTIST, for Co₃W₂ : Co^II−HS⋅⋅⋅W^V (S_Co(II)-HS=³/₂ and S_W(V)=¹/₂)→Co^III−LS⋅⋅⋅W^IV (S_W(IV)=0 and S_Co(III)-LS=0). These comprehensive studies shed light on the water-solvation-dependent spin transitions in Co(II)-octacyanidometallate(IV/V) complexes.     

A combinatorial chemistry approach to new materials for non‐linear optics. I. Five Schiff bases

A combinatorial chemistry approach has been used to synthesize an array of Schiff bases, five of which, namely N‐[(E,2E)‐3‐(4‐methoxy­phenyl)‐2‐propenyl­idene]‐3‐nitro­aniline, C₁₆H₁₄N₂O₃, (1a), N‐[(E,2E)‐3‐(4‐methoxy­phenyl)‐2‐propenyl­idene]‐4‐nitro­aniline, C₁₆H₁₄N₂O₃, (2a), N‐{(E,2E)‐3‐[4‐(di­methyl­amino)­phenyl]‐2‐propenyl­idene}‐3‐nitro­aniline, C₁₇H₁₇N₃O₂, (1b), N‐{(E,2E)‐3‐[4‐(di­methyl­amino)­phenyl]‐2‐propenyl­idene}‐4‐nitro­aniline, C₁₇H₁₇N₃O₂, (2b), and N‐{(E,2E)‐3‐[4‐(di­methyl­amino)­phenyl]‐2‐propenyl­idene}‐2‐methyl‐4‐nitro­aniline, C₁₈H₁₉N₃O₂, (3b), have been structurally characterized. A stack structure is observed for (1a) and (1b) in the crystal phase. Experimental and calculated molecular structures are discussed for these compounds which belong to a chemical class having potential applications as non‐linear optical materials.     

Polyol-Metall-Komplexe. 25. rac-Mannose,rac-Arabit und L-Threit als deprotonierte Liganden in Ferraten(III)

Polyol Metal Complexes. 25. rac-Mannose, rac-Arabitol and L -Threitol as Deprotonated Ligands in Ferrates(III ) Ba₂[Fe₂(β-rac-ManfH_?5)₂] · 12H₂O ( 1 ), Sr₄[Fe₄(rac-Arab1,2,3,5H_?4)₄(OH)₂]CO₃ · 33 H₂O ( 2 ), and Ba₂[Fe₂(L-ThreH_?4)₂(OH)₂] · 12.5 H₂O ( 3 ) (Man = mannose, Arab = arabitol, Thre = threitol) have been crystallized from alkaline aqueous solution. Crystal structure analysis revealed dinuclear ferrate(III ) ions for 1 and 3 , the former being a C_i-symmetrical homoleptic ferric complex with pentadentate pentaanions derived from racemic β-mannofuranose. In 3 , besides tetradentate L -threitolato ligands, there is one terminal hydroxo ligand at each ferric center. Hydroxo ligands are also present in the C_i-symmetrical hexaanions of 2 , which are tetranuclear planar entities built up from four edge-sharing FeO₆ octahedra. However arabitol is a pentitol, the tetraanionic ligands are only tetradentate for steric reasons.     

Modification of olefin polymerization catalysts. I. Mechanism of the interaction between AIEt3 and silyl ethers

The interaction between AlEt₃ and silyl ethers, Ph_nSi(OMe)_4-n (n = 0–3), was followed by ¹³C- and ²⁹Si-NMR techniques in conditions close to those typical for an olefin polymerization reaction with supported Ziegler–Natta catalysts (A1Et₃:silyl ether ratios from 1 to 10, temperature range 25–75°C). A1Et₃ and silyl ethers form instantaneously at ambient temperature a donor-acceptor complex, which is stable at a 1:1 molar ratio. In the presence of excess A1Et₃ the complex decomposes via a mechanism consisting, in the case of PhSi(OMe)₃, of five consecutive steps: alternating complexation and ether reductions with the formation of alkylated silyl ethers, Ph(Et)_nSi(OMe)_3-n (n = 1,2), and dialkyl-aluminum alkoxides, (Et₂A1OMe₃)_n (n = 2,3). The rate of decomposition was enhanced by the increasing number of methoxy groups present in the silyl ether, heating, or a high A1Et₃:silyl ether ratio. The decomposition was not inhibited by the presence of 1-hexene.     

Beiträge zur Chemie des Phosphors. 159. Über die Reaktion des Diphosphaborirans (t-BuP)2BN(i-Pr)2 mit Kalium bzw. Kaliumnaphthalid

Contributions to the Chemistry of Phosphorus. 159. On the Reaction of the Diphosphaborirane (t-BuP)₂BN(i-Pr)₂ with Potassium or Potassium Naphthalenide The reaction of (t-BuP)₂BN(i-Pr)₂ with potassium or K-naphthalenide in tetrahydrofuran leads to K(t-Bu)P? ;BN(i-Pr)₂? P(t-Bu)K ( 1 ) via P? ;P bond cleavage of the three-membered ring skeleton. Above ? 78°C 1 changes into the asymmetric compound K(t-Bu)P? ;P(t-Bu)? BHN(i-Pr)₂ ( 2 ). In dimethoxyethane additionally the monometallated diphosphaborirane K(t-Bu)P₂BN(i-Pr)₂ ( 3 ) is formed. 1 and 3 , which could be isolated free from other phosphorus containing compounds, as well as the corresponding silylphosphanes Me₃Si(t-Bu)P? ;BN(i-Pr)₂? ;P(t-Bu)SiMe ₃ ( 4 ) and Me₃Si(t-Bu)P₂BN(i-Pr)₂ ( 5 ) were characterized by NMR spectroscopy. Protolysis of 3 or 5 leads to a decomposition of the three-membered ring skeleton with formation of H(t-Bu)P? ;PH₂.     

The adamantane rearrangement of 1,2-trimethylenenorbornanes. Part IV. Hydride-ion abstraction in 1,2-exo-trimethylenenorbornane

In the AlBr₃-catalyzed adamantane rearrangement in CS₂ of 1,2-exo-trimethylenenorbornane ( 1 ) to 2-endo,6-endo-trimethylenenorbornane ( 3 ), hydride-ion abstraction occurs at C(6) from the exo-side. The k_H/k_D value for competition between 1 and 5 (D_exo-C(6)) was 1.58 ± 0.05, whereas no kinetic isotope effect was operative for competition between unlabeled 1 and 4 (D_endo-C(5)) and between 1 and 6 (D_endo-C(6)).     

Beiträge zur Chemie des Phosphors. 134. Über die Triphosphane H(t-BuP)3H,Li(t-BuP)3Li und Me3Si(t-BuP)3SiMe3

Contributions to the Chemistry of Phosphorus. 134. On the Triphosphanes H(t-BuP)₃H' Li(t-BuP)₃Li, and Me₃Si(t-BuP)₃SiMe₃ The reaction of 1,3-diiodo-1,2,3-tri-tert-butyltriphosphane, I(t-BuP)₃I, with lithium aluminium hydride leads to 1,2,3-tri-tert-butyltriphosphane, H(t-BuP)₃H ( 1 ). 1 reacts with n-butyllithium to 1,3-dilithium-1,2,3-tri-tert-butyltriphosphide, Li(t-BuP)₃Li ( 2 ), which reacts further with trimethylchlorosilane yielding 1,3-bis(trimethylsilyl)-1,2,3-tri-tert-butyltriphosphane, Me₃Si(t-BuP)₃SiMe₃ ( 3 ). The triphosphanes 1, 2 and 3 could be isolated in a pure state. In solution 1 forms the threo, threo and the threo,erythro configurated diastereomers 1a and 1b in a ratio of about 2:1. 3 predominantly exists in form of the threo,erythro configurated diastereomer 3b by steric reasons.     

Oligosaccharide Analogues of Polysaccharides. Part 1. Concept and synthesis of monosaccharide-derived monomers

It is proposed to study the influence of interresidue H-bonds on the structure and properties of polysaccharides by comparing them to a series of systematically modified oligosaccharide analogues where some or all of the glycosidic O-atoms are replaced by buta-1,3-diyne-1,4-diyl groups. This group is long enough to interrupt the interresidue H-bonds, is chemically versatile, and allows a binomial synthesis. Several approaches to the simplest monomeric unit required to make analogues of cellulose are described. In the first approach, allyl α-D -galactopyranoside ( 1 ) was transformed via 2 and the tribenzyl ether 3 into the triflate 4 (Scheme 2). Substitution by cyanide (→ 5–7 ) followed by reduction with DIBAH led in high yield to the aldehyde 9 , which was transformed into the dibromoalkene 10 and the alkyne 11 following the Corey-Fuchs procedure (Scheme 3). The alkyne was deprotected via 12 or directly to the hemiacetal 13 . Oxidation to the lactone 14 , followed by addition of lithium (trimethylsilyl)acetylide Me₃SiC?CLi/CeCl₃ (→ 15 ) and reductive dehydroxylation afforded the disilylated dialkyne 16 . The large excess of Pd catalyst required for the transformation 11 → 13 was avoided by deallylating the dibromoalkene 10 (→ 17 → 18 ), followed by oxidation to the lactone 19 , addition of Me₃SiC?CLi to the anomeric hemiketals 20 (α-D /β-D 7:2), dehydroxylation to 21 , and elimination to the monosilylated dialkyne 22 (Scheme 3). In an alternative approach, treatment of the epoxide 24 (from 23 ) with Me₃SiC?CLi/Et₂AlCl according to a known procedure gave not only the alkyne 27 but also 25 , resulting from participation of the MeOCH₂O group (Scheme 4). Using Me₃Al instead of Et₂AlCl increased the yield and selectivity. Deprotection of 27 (→ 28 ), dibenzylation (→ 29 ), and acetolysis led to the diacetate 30 which was partially deacetylated (→ 31 ) and oxidized to the lactone 32 . Addition of Me₃SiC?CLi/TiCl₄ afforded the anomeric hemiketals 33 (α-D /β-D 3:2) which were deoxygenated to the dialkyne 34 . This synthesis of target monomers was shortened by treating the hydroxy acetal 36 (from 27 ) with (Me₃SiC?C)₃Al (Scheme 5): formation of the alkyne 37 (70%) by fully retentive alkynylating acetal cleavage is rationalised by postulating a participation of HOC(3). The sequence was further improved by substituting the MeOCH₂O by the (i-Pr)₃SiO group (Scheme 6); the epoxide 38 (from 23 ); yielded 85% of the alkyne 39 which was transformed, on the one hand, via 40 into the dibenzyl ether 29 , and, on the other hand, after C-desilylation (→ 41 ) into the dialkyne 42 . Finally, combined alkynylating opening of the oxirane and the 1,3-dioxolane rings of 38 with excess Et₂Al C?CSiMe₃ led directly to the monomer 43 which is thus available in two steps and 77% yield from 23 (Scheme 6).     

Polyethers. I. Polymerization of 2-methyl-2-butene oxide

2-Methyl-2-butene oxide (2,3-epoxy-2-methylbutane) was polymerized with modified alkylaluminum initiators a t low temperatures to a high-melting, crystalline, film-forming polymer. High yields and comparatively high molecular weights were obtained with Al(i-Bu)₃?xH₂O initiators in inert diluents. When such initiators were modified with acetylacetone they became ineffective. Ammonia could be substituted for water in formulating an active initiator. Attempts to prepare an active initiator in the presence of the monomer were unsuccessful indicsting competition with the water for Al(i-Bu)₃. Thermal decomposition of the polymer produced methyl isopropyl ketone with some pivaldehyde.     

Monomer-isomerization polymerization. XVII. Monomer-isomerizations copolymerizations of 2-butene with 3-heptenes and 4-methyl-2-pentenes with Ziegler-Natta catalyst

2-Butene(2B) copolymerizes with 3-heptene(3H) and 4-methyl-2-pentene(4M2P) by a monomer-isomerization copolymerization mechanism in the presence of TiCl₃–(C₂H₅)₃Al catalyst at 80°C to yield the copolymers of 1-olefin units. By comparison, the copolymerization of 1-butene(1B) with 4-methyl-1-pentene(4M1P) was also carried out under similar conditions. The composition of the copolymers obtained from these copolymerizations was determined from the ratios of optical densities D₇₂₃/D₁₃₈₀ and D₁₁₇₀/D₁₃₈₀ in their infrared (IR) spectra. The apparent monomer reactivity ratios for the monomer-isomerization copolymerization of 2B with 3H and 4M2P, in which the concentration of olefin monomer in the feed was used as 2-olefin, were determined as follows: cis-2B(M₁)/3H(M₂); r₁ = 4.00, r₂ = 0.20: trans-2B(M₁)/3H; r₁ = 3.50, r₂ = 0.20; 4M2P(M₁)-trans-2B(M₂): r₁ = 0.05, r₂ = 9.0. These results indicate that the isomerization of 2-olefins to 1-olefins was important to monomer-isomerization copolymerization.     

Triaziridine 7. Mitteilung. Stabile pyramidale Konfigurationen an den Stickstoff-Atomen von Dialkyl-und Trialkyl-triaziridinen

Stable Pyramidal configurations at the Nitrogen Atoms of Dialkyl-and Trialkyl-triaziridines Stereochemical features of the recently synthesized nine samples of di- and trialkyl-triaziridines, namely the 1,3-cyclopentylen-(series a ) and the two stereoisomers of the diisopropyl derivatives (series b and c ), containing as the third substituent an H-atom ( 2 ), a CH₃ group ( 3 )or a CH₂OH group ( 4 ), were elaborated on the basis of the ¹H-, ¹³C-, and ¹⁵N-NMR spectra. The three N-atoms of the saturated N₃-homocycle were found to be stable to pyramidal inversion in all cases. According to their NMR spectra, 2 – 4 of the series a and b possess twofold symmetry (C_s), while 2 – 4 of series c are asymmetric. Thus, series c has the trans-configuration at N(2)/N(3) and, consequently, the cis-configuration at N(1)/N(2), while series a and b have the cis-configuration at N(2)/N(3) and -since the all-cis-arrangement is excluded-the trans-configuration at N(1)/N(2). The asymmetry of the trans-configurated 2c turned into twofold symmetry (C₂), when a little CF₃COOH was added. The ¹H- and ¹³C-NMR data of series b and c of our alkyl-triaziridines exhibit a shielding effect, according to which there are two types of i-Pr groups, i-Pr(a) and i-Pr(b). They differ in the NMR signals of the H- and the C-atoms of their CH groups: the H-atoms of i-Pr(a) are more deshielded by 0.75–1.111 ppm and its C-atoms are more shielded by 10.0–160.0 ppm as compared to the corresponding atoms of i-Pr(b). i-Pr(a) is cis (on the N₃-homocycle) to a large substituent (such as i-Pr, Me, CH₂OH) and to a lone pair, while i-Pr(b)is cis only to a small (H) or to no substituent and to one or two lone pairs. An analogous effect appears in the NMR signals of the CH₃ and CH₂OH groups at N(1) of 3 and 4 in the series b and c .