1-methyl-(D3)-trishomocubane

The acid catalysed rearrangement of 8-methyl-pentacyclo(5.4.0.0^2,6.0^3,10.0^5,9)undecan-8-endo-o1 ($\text{8}$) to 3-methyl-(D₃)-trishomocuban-4-o1 ($\text{9}$) provided the key step to the synthesis of the title compound ($\text{11}$).     

Chiral synthesis of (2s,3s,7s)-3,7-dimethylpentadecan-2-yl acetate and propionate,potential sex pheromone components of the pine saw-fly neodiprion sertifer (geoff.)

A synthesis of (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate ($\text{2}$) and propionate ($\text{3}$) is described. (2S)-2-Methyldecan-1-yl lithium ($\text{5}$) was reacted with (3S,4S)-3,4-dimethyl-γ-butyrolactone ($\text{6}$) to yield the ketoalcohol $\text{19}$ which upon Huang-Minlon reduction furnished (2S,3S,7S)-3,7-dimethylpentadecan-2-ol ($\text{1}$). Acylations gave the esters $\text{2}$ and $\text{3}$. The (2S)-2-methyldecan-1-yl lithium was obtained via asymmetric synthesis. The chiral lactone $\text{6}$ was obtained from (2S,3S)-trans-2,3-epoxybutane and dimethyl malonate.     

6-alkyl- and 5,6-dialkyl-2-methoxy-4(3H)-pyrimidinones in the transformations of pyrimidines. Regiospecific 1-N-acylation of pyrimidines.

Transformation of 6- and 5,6-dialkyl-2-methoxy-4(3H)-pyrimidinones (1a and 1b) into 1-$\text{N}$-acylated-pyrimidine derivatives 3($\text{a}$-$\text{f}$) under Friedel-Craft like conditions is presented. In different acylation conditions 4-O-acylated-pyrimidines (5a and 5b) are also obtained. Compounds (3c) and (3f) can be directly converted into 1-$\text{N}$-acyl-protected-isouridine analogues (8a and 8b).     

Etude des equilibres solide-liquide des systems MIPO3Sm(PO3)3 (MI = Li,Na, Ag)

The M^IPO₃Sm(PO₃)₃(M^I = Li, Na, Ag) systems were studied. Differential thermal analysis and X-ray diffraction were used to investigate the liquidus and solidus relations. Three compounds LiSm(PO₃)₄, NaSm(PO₃)₄, and AgSm(PO₃)₄ were obtained which melt incongruently at 1248, 1143, and 1078 K, respectively. These compounds are isomorphous with their homologs LiLn(PO₃)₄, NaLn(PO₃)₄, AgLn(PO₃)₄ (Ln = Ce, La, Nd). They belong to the monoclinic system. The LiSm(PO₃)₄ unit cell parameters refined by least squares method are a = 16.43(3) Å, b = 7.16(1) Å, c = 9.65(3) Å, β = 125,9°(1), with the space group $\text{C2}\text{c}$ and Z = 4. NaSm(PO₃)₄ and AgSm(PO₃)₄ are isotypic; they cristallize in the $\text{P2}{}_1\text{c}$ space group, Z = 4; their unit cell parameters are, respectively, a = 12.18(1) Å, b = 13.05(1) Å, c = 7.25(5) Å, β = 126,53°(4), $\text{a = 12.25(1)}\text{A}\text{?}$, b = 13.06(1) Å, c = 7.201(9) Å, β = 126,57°(7). The ir spectra of the last two compounds indicate that these phosphates are chain phosphates.     

Regiospecific introduction of a branched-chain to kanamycin B and stereospecific transformation of the 2,6-diamino-2,6-dideoxy-D-glucopyranosyl moiety into 2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-l-arabino or lyxo-hexopyranosyl,or 2-amino-2,3,4,6-tetradeoxy-5-C-methyl-L-threo-hexopyranosyl

4-O-(2,6-diamino-2,3,4,6-tetradeoxy-3-C-methyl-β-L-arabino and lyxo-hexopyranosyl) and 4-O-(2-amino2,3,4,6-tetradeoxy-5-c-methyl-L-threo-hexopyranosyl-6-O-(3-amino-3-decxy-α-D-glucopyranosyl)-2-deoxystreptamine ($\text{6}$, $\text{7}$ and $\text{12}$) were synthesized from a kanamycin B derivative ($\text{1}$) by regiospecific methylation and stereospecific hydrogenation followed by removal of masking groups, converting a D-sugar moiety (4-O-glycoside portion) into L-sugar. The usual conformation of $\text{6}$ and $\text{7}$ were determined as boat and skew by 250 MHz PMR spectra respectively.     

Structure and synthesis of physoperuvine: x-ray crystal and molecular structures of the n-benzoyl derivatives of (±)-3- and (+)-4-methylaminocycloheptanone

Single-crystal X-ray analyses have defined the structures and solid-state conformations of (±)-N-benzoyl-3-methylaminocycloheptanone [(±)-$\text{3}$]and (+)-N-benzoyl-4-methylaminocycloheptanone [(±)$\text{4}$]. Resolution of (±)-[4- methylaminocycloheptanone α 1-hydroxytropane]to yield the (+)-enantiomer. Identical in all respects with the free base from natural (+)-physoperuvine, was achieved via the di-p-toluoyl-(+)-tartrate salt.     

A short and efficient synthesis of 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones

The cycloaddition of α,β-epoxyaldehydes or ketones ($\text{2}$) with the ketene acetal MeHC=C(OMe)₂ ($\text{1}$) gives epoxyoxetanes ($\text{3}$) in high yields. Without isolation they can be transformed into 4-hydroxy-5-(1-hydroxyalkyl)-γ-butyrolactones ($\text{6}$) via the epoxy esters $\text{4}$ and trihydroxy esters ($\text{5}$). The lactones $\text{6}$ appear to be valuable precursors for the synthesis of 5-(1-hydroxyalkyl)-3-methyl-2-5H-furanones ($\text{7}$) and 3-methyl-5-ylidene-2-5H-furanones ($\text{8}$)     

Palladium-catalyzed asymmetric cyclization of methyl (E)-oxo-9-phenoxy-7-nonenoate and its analogs

Asymmetric cyclizations of methyl (E)-3-oxo-9-phenoxy-7-nonenoate ($\text{1}$) or methyl (E)-3-oxo-9-(methoxycarbonyl)oxy-7-nonenoate ($\text{4}$) without added base were carried out in the presence of a catalytic amount of palladium(II) acetate and chiral diphosphine as ligands. Allylic carbonate $\text{4}$ reacted by use of Pd(OAC)₂-(S)-(R)-BPPFA at room temperature to give (R)-3-vinylcyclohexanone ($\text{3}$), after decarboxylation, in up to 48% e. e.     

Stereochemical consequence in the elimination of β-hydroxyalkylsilanes: Stereoselective formation of (Z)- and (E)-alkylidene-γ-butyrolactones

Titanium(IV) chloride-mediated reaction of 4,5-dihydro-2-(trimethylsiloxy)-3-(trimethylsilyl)furan (1a) with acetaldehyde gave $\text{diastereomerically pure}$ (3S^*, 1′R^*)-4,5-dihydro-3-(1′hydroxyethyl)-3-(trimethylsilyl)-2(3$\text{H}$)furanone (2a), which afforded selectively either (Z)- or (E)-α-ethylidene-γ-butyrolactone (3a) under proper conditions. Facile isomerization of 2a into $\text{diastereomerically pure}$ (3S^*, 1′R^*)-4,5-dihydro-3-&{1′-(trimethylsiloxy)ethyl}-2(3$\text{H}$)furanone (4) suggests an intriguing stereochemical outcome from 2a to (E)-3a via an enolate of 4.     

Reaction of 3-azido-5-phenyl-1,2,4-oxadiazole with dimethylformamide,a new deoxygenative coupling reaction

When 3-bromo-5-phenyl-1,2,4-oxadiazole (1b) is heated with sodium azide in anhydrous dimethylformamide at 130°, 3-dimethylamino-($\text{1c}$) and 3-dimethylaminomethyleneamino-5-phenyl-1,2,4-oxadiazole ($\text{1d}$) are formed, the latter by a new deoxygenative coupling of the azide ($\text{1a}$), or the nitrene derived from it, with the solvent.     

Marine natural products: fistularin-1, -2 and -3 from the sponge Aplysina fistularis forma fulva

Three new high molecular weight bromotyrosine-related metabolites, $\text{3a}$, $\text{4a}$ and $\text{5a}$, were isolated from the sponge Aplysina ( Verongia) fistularis forma fulva, and their structures were determined from high resolution ¹H NMR and other spectroscopic data. The new metabolites are formally derived by combination of major segments of two known Aplysina metabolites $\text{1a}$ and $\text{2}$.     

The octant rule. XVI1. COnformation and circular dichroism of syn and anti 2-methylbicyclo[3.1.0]hexan-3-ones,thujone and isothujone

(lS,5S)-exo-2(R)-Methylbicyclo[3.1.0]hexan-3-one ($\text{1}$) and (lS,5S)-endo-2(S)-methylbicyclo[3.1.0]hexan-3-one (2) were synthesized and their circular dichroism (CD) spectra run. Conformational analysis based on molecular mechanics calculations and Karplus equation analyses of vicinal H¦H NMR coupling constants indicate boat-like sofa conformations for both $\text{1}$ and $\text{2}$, with very little ring distortion from the symmetry of the parent bicyclo[3.1.0]hexan-3-one. The lone dissymmetric ψ-axial and ψ-equatorial methyl groups of $\text{1}$ and $\text{2}$, respectively, are both octant consignate. The natural product analogs of $\text{1}$ and $\text{2}$, (?)-3-isothujone ($\text{3}$) and (+)-3-thujone ($\text{4}$) were prepared and examined similarly. Their α-methyl perturbers dominate the CD n-π^★ Cotton effects.     

1,6-dihydro-3(2H)-pyridinones as synthetic intermediates. Total synthesis of (±)-tecomanine

The first and stereoselective total synthesis of (±)-tecomanine ($\text{1}$) has been achieved from ethyl 1,6-dihydro-3(2H)-pyridinone-1-carboxylate ($\text{2}$) as a synthon.     

Pyrolysis of homoadamant-3-ene

Pyrolysis of homoadamant-3-ene ($\text{5}$), generated from 1-adamantylcarbene ($\text{7}$), leads to the same three olefins ($\text{2}$, $\text{3}$, and $\text{4}$) that are produced from pyrolysis of 3-homoadamantyl acetate ($\text{1}$).     

Nucleosides-126: Selective methylation of the C-nucleoside, ψ-isocytidine and its 2$́-deoxy analog. Synthesis of 1-methyl, 3-methyl and 4-o-methyl derivatives

Methods were developed to prepare 1 -methyl-, 3-methyl- and 4-0-methyl-ψ-isocytidine by selective methylation.3$\text{,}\text{?}$5$\text{-}\text{?}$O-Tetraisopropyldisiloxanyl-ψ isocytidine (8) was trimethylsilylated and then treated with MeI and, after deprotection, 1 -methyl-ψ isocytidine (6) was obtained. The 2$\text{-}\text{?}$deoxy analog (7) was also prepared in a similar manner from the 2$\text{-}\text{?}$deoxy analog (10) of 8. Treatment of 8 with CH₂N₂ afforded the 3-methyl-ψ-isocytidine derivative (19) as the major product. Methylation with diazomethane also occurred mainly on N3 of the 2$\text{-}\text{?}$deoxy analog 10 to form 20. Removal of the 3$\text{,}\text{?}$ 5$\text{-}\text{?}$O-protecting group from 19 and 20 afforded 3-methyl-ψ-isocytidine (14) and its 2-deoxy analog (15), respectively. 2-N-Acetyl- 3$\text{,}\text{?}$5$\text{-}\text{?}$O-tetraisopropyldisiloxanyl-ψ-isocytidine (24), on the other hand, gave the 4-O-methyl derivative (25) as the major product upon CH₂N₂ treatment. Subsequent deprotection of 25 afforded 4-O-methyl-ψ-isocytidine (29). aiv51b1p33b     

Monoclinic-trigonal transition in some MI3M′III(XO4)3 compounds: The high temperature form of (NH4)3In(SO4)3

The high-temperature form of (NH₄)₃In(SO₄)₃ is rhombohedral, R3c, with a = 15.531 (12), c = 9.163 (8)Å, Z = 6. The structure was solved to R = 0.023 for 570 independent reflections measured at about 140°C. The structure is built up of [In(SO₄)₃]_∞ columns extending along the c axis and composed of InO₆ octahedra and SO₄ tetrahedra linked together; this arrangement is very similar to that found in the low-temperature form. To explain the transition mechanism, the existence of an intermediate phase of point symmetry $\text{3}$ is postulated and the whole sequence of possible forms would be $\text{2}\text{m}\text{→}\text{3}\text{→ 3m →}\text{3}\text{m}$. This last phase would be the prototypic structure of the possibly ferroelastic low-temperature modification, which can apparently exist only with nonspherical monovalent cations.     

2-cyano Δ3 piperidines vi1 : a general method for the stereoselective synthesis of cis and trans 2,6-dialkylpiperidine alkaloids

The cis 2,6-dialkylpiperidine alkaloid (±) dihydro-pinidine $\text{7b}$ and the trans alkaloid (±) solenopsin A $\text{5a}$ were synthesized from a common α-aminonitrile synthon $\text{1}$. The key step in this synthesis was the stereoselective reductive decyanation of the 1-benzyl-2cyano-2′, 6-dialkylpiperidines $\text{3a}$ and $\text{3b}$.     

Trimethymetall-urotropinaddukte des aluminiums,galliums, indiums und thalliums

Reactions of urotropine (C₆H₁₂N₄) with trimethylmetal derivatives of Al, Ga, In und Tl in various ($\text{1}\text{1}$$\text{1}\text{4}$) molar ratios lead to stable and monomeric $\text{1}\text{1}$, $\text{1}\text{2}$ or $\text{1}\text{3}$ adducts in good yields, but no $\text{1}\text{4}$ addition product could be isolated. The vibrational spectra (IR and Raman) of all compounds are recorded and partly assigned. Some characteristic frequencies of the C₆N₄-skeletons clearly show the symmetry changes in the series of the $\text{1}\text{1}$ → $\text{1}\text{2}$ → $\text{1}\text{3}$ adducts (C_3ν → C_2ν → C_3ν). The X-ray structure determinations of C₆H₁₂N₄·.GaMe₃ (MeCH₃) and C₆H₁₂N₄·.2GaMe₃, are in good agreement with the vibrational spectra. Both compounds crystallize in monoclinic space groups (P2₁ and C2/c). The GaN distances are around 214 pm, and the values for the C₆N₄-skeletons are not significantly different from those for free urotropine.     

(Cr3AsO13)3−: Un nouveau type d'anion condensé. Préparation chimique et données cristallographiques sur (NH4)2HCr3AsO13

(NH₄)₂HCr₃AsO₁₃ is monoclinic ($\text{P2}{}_1\text{c}$) with a tetramolecular unit cell: a = 13.99(1), b = 9.47(1), c = 9.55(1) Å, and β = 93.10(1)°. We describe the chemical preparation and give crystal data for this compound.     

Phase equilibrium relations in the binary systems LiPO3CeP3O9 and NaPO3CeP3O9

The LiPO₃CeP₃O₉ and NaPO₃CeP₃O₉ systems have been investigated for the first time by DTA, X-ray diffraction, and infrared spectroscopy. Each system forms a single 1:1 compound. LiCe(PO₃)₄ melts in a peritectic reaction at 980°C. NaCe(PO₃)₄ melts incongruently, too, at 865°C. These compounds have a monoclinic unit cell with the parameters: a = 16.415(6), b = 7,042(6), c = 9.772(7)Å; β = 126.03(5)°; Z = 4; space group $\text{C}{}_2\text{c}$ for LiCe (PO₃)₄; and a = 9.981(4), b = 13.129(6), c = 7.226(5) Å, β = 89.93(4)°, Z = 4, space group $\text{P2}{}_1\text{n}$ for NaCe(PO₃)₄. It is established that both compounds are mixed polyphosphates with chain structure of the type |M^I_IM^III_II (PO₃)₄|_∞M^I_I: alkali metal, M^III_II: rare earth.