Reactions of perfluoronitriles. II. Interactions with phenylphosphine

Treatment of perfluoro-n-octanonitrile with phenylphosphine gave tetraphenyltetraphosphine and a spectrum of reduction and interaction products. Fifteen compounds were identified. The imine, (R_fC₇F₁₅) R_fCHNH, and the amine, R_fCH₂NH₂, were the primary reduction products. Secondary phosphorus-free products, some formed following ammonia evolution, were the following: R_fCHNCH₂R_f, R_fCH₂CH(NH₂)R_f, R_fC(NH)NCR_f(NH₂), R_fCH₂NHCR_f(NH), (R_fCN)₃, R_fCHNCR_fNCR_f(NH), R_fCH₂NCR_fNHCH₂R_f, and R_fCH₂NCR_fNHCR_f(NH). Only three phosphorus-containing materials were definitely identified: R_fCH(NH₂)P(C₆H₅)H, R_fCH[P(C₆H₅)H]NCHR_f, and R_fC(NH)P(C₆H₅)CR_f(NH). Depending on reaction conditions, specific phosphorus-containing compounds could be preferentially produced. All the structure assignments are based solely on mass spectral breakdown patterns, since pure compounds were not isolated.     

Thiocyanatomercuration des acetyleniques. Synthese de derives β-(iso)thiocyanatoalcenyl mercuriques,d'α-halo β-thiocyanato alcenes et de thiocyanato-1 alcynes-1

In the presence of (SCN)^? mercuric chloride HgCl₂ adds to acetylenic compounds R¹CCR² affording in most cases α-chloromercuri-β-thiocyanatoalkenes R¹C(SCN)C(R²)HgCl and if R¹ = R² = Et or n-Bu isothiocyanates R¹C(NCS)C(R²)HgCl. The action of halogens or thio compounds affords α-halo-β-thiocyanatoalkenes. Most of the reported reactions are regio- and stereo-specific, in particular both RC(SCN)CHBr and RCBrCHSCN may be regiospecifically obtained from 1-alkynes RCCH. The synthesis of 1-thiocyanato-1-alkynes is also reported.     

Übergangsmetall—methylen-komplexe: LIX. Ein neues darstellungsverfahren für vinyliden-komplexe

The diazo olefins N₂CCR₂ (R/R = CH₃/CH₃ and (CH₂)₅, respectively), generated in situ from the corresponding cyclic N-nitrosourethanes 2a, 2b, are suitable precursors for the corresponding vinylidene ligands 6CCR₂. Thus, treatment of the RhRh complex [(η⁵-C₅Me₅)Rh(μ-CO)]₂ (1) with 2a, 2b in the presence of lithium ethoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR₂)[(η⁵-C₅Me₅)Rh(CO)]₂ (3a, 3b). This procedure extends the well-documented diazoalkane method for synthesis of μ-alkylidene complexes to the less stable diazoalkenes*     

Alkylsilver(I) induced 1,5-substitution in functionally conjugated enynes. a novel route to cumulated trienes

Functionally conjugated enynes, H₂CC(R¹)CCCR²R₃OS(O)Me, undergo 1,5-substitution with alkylsilver(I) reagents, RAGG ☆ 3 LiBr. The purity of the produced alkylated butatrienes, RCH₂C(R¹)CCCR²R³ depends on the nature of R in RAg ☆ 3 LiBr and on the substituents R¹, R² and R³ in the substrate.     

Übergangsmetall—methylen-komplexe: LXI. Übergangsmetall—vinyliden-komplexe: Neuartige synthese aus diazoalken-vorstufen

The diazoolefines of composition N₂CCR₂ (R/R = CH₃/CH₃ and(-CH₂-)₅) are suitable precursors of the corresponding vinylidene ligands CCR₂. Thus, treatment of the RhRh complex [(η⁵-C₅Me₅)Rh(μ-CO)]₂ (1) with the N-nitrosourethanes 2a and 2b, resp., in the presence of lithium t-butoxide yields the otherwise inaccessible μ-vinylidene complexes (μ-CCR₂)[(η⁵-C₅Me₅)Rh(CO)]₂ (R = CH₃ (3a), R,R = (-CH₂-)₅ (3b)). The analogous cobalt compound (μ-CCMe₂)[(η⁵-C₅Me₅)Co(CO)]₂ (5a) is obtained similarly. This procedure extends the well-documented diazoalkane method for the synthesis of μ-alkylidene complexes to the less stable diazoalkenes. A single-crystal X-ray diffraction study of the dimethylvinylidene derivative 3a shows the CMe₂ ligand to adopt an almost symmetrically metal-bridging position (d(RhC) 197.8(1) and 204.3(1) pm), with a rhodium-rhodium single bond completing a three-membered Rh₂C-metallacycle (d(RhRh) 268.4(0) pm) analogous with cyclopropane.     

Ethylenic compounds reactivity: bromination—XLI: Relative reactivities of R1CMeCH2 and R1CHCMe2 series as a criterion for distinguishing between bridged and acyclic transition states. Degree of symmetry of the bromonium ion-like transition state

Reactivities of homogeneous series of ethylenic compounds R¹CHCH₂1, trans R¹CHCHMe 2, R¹MeCCH₂3 and R¹CHCMe₂4 have been measured in methanol at 25°C (R¹ Me, Et, n-Pr, -CH₂C₆H₅-CH₂OCOCH₃, -CH₂Cl). The criterion developed to decide between a bridged and a carbonium ion-like transition state is based on an internal comparison of the series and avoids resorting to external structural scales. Even in the case of alkenes 3 and 4 which are very dissymmetric with respect to polarity, the sensitivity to polar effects remains constant and the transition state behaves like a symmetric entity; only a slight secondary effect, attributed to hyperconjugation, is detectable.     

Some unexpected reactions of perfluoroalkynylmagnesium halides

R_FCCMgX reacts with Ac₂O to give not only MeC(O)CCR_F but also MeC(O)CXC(R_F)C(O)Me, and with CF₃COOPr it gives CF₃C(O)CHC(OPr)R_F not CF₃C(O)CCR_F; R_FCCMgBr reacts with Cl₂ to give R_FCCBr rather than R_FCCCl, while with Br₂ R_FCCMgI similarly gives R_FCCI rather than R_FCCBr.     

Zur reaktion von metall-koordiniertem kohlenmonoxid mit yliden : VII. Trimethylphosphoranylidenmethyl(trimethylsiloxy)carben-komplexe von chrom,molybdän und wolfram: aufbau einer metallvinyl-einheit durch c(carbanion)c(carben)-π-wechselwirkung und photochemische e/z-isomerisierung

The treatment of the hexacarbonylmetal compounds M(CO)₆ (M = Cr. Mo, W) with two equivalents Me₃PCH₂ yields the phosphonium acylmetalphosphorus ylides Me₄P[(CO)₅MC(O)CHPMe₃] 1a–1c. Their reaction with Me₃SiOSO₂CF₃ leads via O-silylation to formation of the neutral “siloxy(ylidecarbene) complexes” (CO)₅MC(OSiMe₃)CHPMe₃2a–2c, which are protonated by HX (X = Cl, CF₃SO₃) to give the thermolabile carbene complexes [(CO)₅MC(OSiMe₃)H₂CPMe₃]X, 3a, 3b. ¹H, ¹³C NMR and IR data suggest, that delocalization of the ylidic charge to the carbene carbon generates a metal-coordinated vinyl group in the case of 2a–2c. In addition this fact is proved by the X-ray analysis of 2c, for which a C(ylide)C(carbene) bond distance of 133 pm is found. 2a–2c are obtained as pure E-isomers but can be converted to the Z-isomers 2a′–2c′ upon photolysis.     

gem-Difluoroallyllithium: Preparation by the transmetalation procedure and some reactions

3,3-Difluoroallyltrimethyltin has been prepared by the reaction of β-trimethylstannylethylidenetriphenylphosphorane with chlorodifluoromethane. This tin compound reacts with n-butyllithium in tetrahydrofuran at -95°C to generate gem-difluoroallyllithium. The latter, however, is not stable in solution at that temperature. If generated in situ in the presence of a triorganochlorosilane, products of the type R₃SiCF₂CHCH₂ are obtained in good yield. Addition to the CO bond of 3-pentanone to give (C₂H₅)₂C(OH)CF₂CHCH₂ was achieved by the method of alternate, incremental additions.     

Silylation as a protective method in acetylene chemistry. : Syntheses in the polyeneyne series,R3Si(CC)n(CHCH)4(CC)nSiR3 and H(CC)n(CHCH)4(CC)nH (n = 1, 2)

The Grignard reagents R₃Si(CC)_nMgBr (R = Me, n = 1; R = Et, n = 1,2) couple with cyclooctatetraene dibromide 1 in THF to give, as major products, the silyl-stabilised E, Z, Z, E-polyeneynes, Me₃SiCC(CHCH)₄CCSiMe₃3a, Et₃SiCC(CHCH)₄CCSiEt₃4a and Et₃Si(CC)₂(CHCH)₄(CC)₂SiEt₃6a together with minor proportions of configurational isomers Z, E, Z, Z 3c, all -E 3b, 4b, 6b and compounds in which a bicyclo-octadiene structure 2, 5 and 7 is retained. Irradiation converts the cis(Z)-rich isomers e.g. 3c into the all-trans(E) products. Treatment of the bissilyl compounds 3, 4 and 6 with aqueous base liberates the respective parent polyeneynes, H(CC)_n(CHCH)₄(CC)_nH, in each case.     

Reactions of cationic vinylidene complexes [Fe{=C=C(R1)R2}(η-C5H5)(dppm)]+[dppm = bis(diphenylphosphino)methane] with nucleophiles: stereoselective synthesis and crystal structure of the alkenyl complex (E)-[Fe{C(H)=C(Me)Ph}(η-C5H5)(dppm)]

The reactivity of the cationic vinylidene complexes [Fe{CC(R¹)R²}(η-C₅H₅(dppm)]⁺ toward different nucleophiles has been investigated. Whereas the disubstituted complexes (R¹ = Me; R² = Ph or ^tBu) are unreactive with water and methanol, the addition of the anion hydride proceeds stereoselectively to give the alkenyl E isomers. The structure of (E)-[Fe{C(H)C(Me)Ph}(η-C₅H₅(dppm)] has been determined by an X-ray diffraction study. Nucleophilic additions to the unsubstituted complex (R¹ = R² = H) have also been examined.     

Olefin isomerisation by group via metals

2-(MeR¹CCR²)-and 2-(CH₂CR¹CH₂CH₂)-pyridine (R¹,R² = H or Me) undergo 1,2-double-bond shifts and 2-(CH₂CHCH₂CH₂CH₂)-pyridine undergoes a 1,3-double-bond shift on displacement of norbornadiene from [M(CO)₄norb] (M = Cr, Mo or W) to give complexes of the type [M(CO)₄LL'] (LL' = 2-(allyl)or 2-(substituted allyl)-pyridine), which do not exhibit conformational isomerism involving the plane of the coordinated olefin.     

New 2-acyl-1,3-dioxane derivatives from (1R)-(−)-myrtenal: stereochemical effect on their relative ability as chiral auxiliaries

Four 3,10-pinanediol derivatives 1a–d, prepared in 50–72% global yields from (1R)-(−)-myrtenal 2, were treated with (RO)₂CHCOR₃ (R₃ = CH₃, Ph) to afford 2-acyl-1,3-dioxanes 3a–f. The latter were submitted to nucleophilic additions using several Grignard reagents to mainly afford carbinols generated by re diastereofacial attack (85–99% yield, ⩾88:12 dr). The lowest diastereoselectivity was observed when PhLi or hydrides were used as nucleophiles. Only an equatorial substituent at C-3 modifies the diastereoselectivity of the nucleophilic additions.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Cobalt metallocycles: IV. Ring opening of cobaltacyclopentadienes by addition of SiH,SH,NH and CH to the diene moiety

Cobaltacyclopentadiene complexes, (η⁵-C₅H₅)(PPh₃)($\text{CoCR}{}^1\text{CR}{}^2\text{CR}{}^2\text{C}$R¹) (R¹, R² =; Ph, Me, CO₂Me), reacted with RH (RH: triethylsilane, thiocresol, dimethyl- and ethylene-thiourea, pyrrole, thiophene) to give diene complexes, (η⁵-C₅H₅)(η⁴-HCR¹CR²CR²CR¹R)Co, or uncomplexed, highly substituted butadiene derivatives, HCR¹CR²CR²CR¹R. The reaction with thiourea proceeded catalytically in the presence of excess of diphenylacetylene although turn-over of the catalyst was small.     

Transition metal complexes of azo compounds V. Complexation and cleavage of the NN bond of diazirines by iron carbonyls

3,3-Dimethyldiazirine and 3,3-pentamethylenediazirine, R₂CN₂, react with enneacarbonyldiiron initially via N-tetracarbonyl intermediates to give dark blue μ-1,2-diazirine-bis(tetracarbonyliron) complexes and small amounts of an Fe₃(CO)₉-cluster of the diazirine. Depending upon the solvent, further reaction may take place by splitting of the NN bond to yield orange (R₂CN)Fe₂(CO)₆(NCR₂) and red (R₂CN)Fe₂(CO)₆(NCO), which contain bridging ketiminato and isocyanato groups. Formation of the latter complexes probably involves “nitrenic” intermediates. A general scheme is proposed for the reactions of the cis-azo group of cyclic azo compounds with iron carbonyls which permits estimation of the product ratio as a function of the ring size of the parent azo ligand. (R₂CN)Fe₂(CO)₆(NCO) adds methanol at room temperature to give (R₂CN)Fe₂(CO)₆(NHCO₂Me).     

Composés propargyliques et alléniques du Si,Ge, Sn chiraux possédant en α un carbone asymétrique mise en évidence des diastéréoisomères

The propargylic R¹R²R³MCH(CH₃)CCH and allenic R¹R²R³MCHCCHCH₃ compounds (M = Si, Ge, Sn) with two neighbouring asymmetric centres exist in two diastereotopic erythro and threo forms observable in NMR.     

Reaction of enyne triflates with nucleophiles

Reaction of nucleophiles with enyne triflates R₁R₂CC(OTf)CCR₃1, via an S_N-2′ process, results in functionalized enynes by way a 1,3-hydride shift from the initially formed butatrienes.     

1-Alkoxy-2-azaallenyl-komplexe von chrom und wolfram

The successive reaction of (CO)₆M with Na[NCR₂¹] and [Et₃O]BF₄ yields (CO)₅M[C(NCR₂¹)OEt] (II: M = Cr; III: M = W; CR₂¹ = C(C₆H₄Br-p)₂ (a), CPh₂ (b), C(C₆H₄OMe-p)₂ (c), C(C₆H₄)₂O (d), CBu₂^tt (e)). Hexacarbonyltungsten, (CO)₆W, reacts with Na[NCPh₂] and MeOSO₂F to give (CO)₅W[C(NCPh₂) OMe] (IV). X-Ray analysis of IIe shows that: (1) the CNC fragment is almost linear (171.7°); (2) the two NC bond lengths are equal within experimental error; and (3) the O,C,Cr,N plane is perpendicular to the C(Me₃),C,N,C(Me₃) plane (90.0°). Therefore compounds II–IV are best described as 1-alkoxy-2-azaallenyl complexes.     

Asymmetrically substituted ferrocene derivatives showing redox switching of optical properties

The electrochemical and spectroelectrochemical behaviors of three ferrocene derivatives, (1) (C₁₈H₃₇)₂NC₆H₄CHCHFcCH₂OH, (2) (C₁₈H₃₇)₂NC₆H₄CHCHFcCHO, (3) (C₁₈H₃₇)₂NC₆H₄CHCHFcCHC(CN)₂, were studied and analyzed on basis of frontier orbital interactions. It was shown that all the three derivatives show two oxidation steps. The first oxidized states of 1 and 2 are stable and show strong LMCT (ligand-to-metal charge transfer) bands. This suggests that they may serve as redox switching of optical properties. In contrast, the first oxidized state of 3 becomes unstable due to strong electron-withdrawing effect of the acceptor substitute.