The stereochemistry of the conversion of (−)-R′3GeCO2H → (−)-R′3GeO2CGeR′3, where R′3Ge  Et(1-C10H7)PhGe, is discussed.

Stereochemistries are assigned to the geometrical isomers of the secondary phosphite 4-methyl-2-oxo-1,3,2-dioxaphosphorinan (I) on the basis of n.m.r. and dipole moment measurements. Chlorination of the isomers of (I) leads stereospecifically to isomers of the chloridate (III). Both isomers of (III) react stereospecifically with piperidine to yield the corresponding piperidide. The cis-form undergoes methanolysis with high stereospecificity whereas the trans-form is methanolysed with low stereospecificity. The stereochemistries of some reactions of the chloridite 2-chloro-4-methyl-1,3,2-dioxaphosphorinan (II) and the phosphite 2-methoxy-4-methyl-1,3,2-dioxaphosphorinan are also described. The interconversion and relative stabilities of the isomers of (I) have been examined.

AbstractAusgehend von dem German (I) (X = H) wird das optisch aktive (R)‐Äthyl‐ (1‐naphthyl)‐phenylgermyllithium (I) (X = Li) dargestellt, das mit Kohlendioxid (III) in die Carbonsäure (I) (X = COOH) übergeführt wird,.die bei Einwirkung von (II) an der Germanium‐Kohlenstoff‐Bindung unter Rückbildung von (I) (X = Li) gespalten und mit Wasser (IV) wieder in das German (I) (X = H) zurückgeführt werden kann.

AbstractDie Umsetzung von optisch aktivem Äthyl‐(1‐naphthyl)‐phenylgermyllithium (I) mit den Alkylhalogeniden (IIa) erfolgt überwiegend unter Erhalt der Kon= figuration am Gerrnanium, im Fall der Alkylhalogenide (IIb) tritt überwiegend Inversion ein.

The preparation of a range of derivatives from the compound (R)(+)-Et(1-C10H7)PhGeH has led to the establishment of the stereochemistries of some nucleophilic substitutions at the germanium atom. For the reactions studied in both silicon and germanium systems, the stereochemistries are identical to those previously established for the Me(1-C10H7)PhSiX compounds.

The interaction of optically active ethyl(1-naphthyl)phenylgermyllithium, R′3-Ge*Li, with alkyl halides, RX, to give optically active R′3Ge*R compounds, occurs with predominant retention of configuration at germanium in the case of MeBr, i-PrCl, i-PrBr, n-BuCl, n-BuBr, t-BuCl, t-BuBr, CH2CHCH2Cl, CH2CHCH2Br and PhCH2Cl, but with predominant inversion in the case of MeI, i-PrI, CH2CHCH2I, PhCH2I, and PhCH2Br. It is suggested that the retention reactions involve direct coupling between R′3Ge*Li and RX, in a four-centre process, while the inversion reactions involve halogen—lithium exchange, to give R′3GeX and RLi, also in a four-centre retentive process, followed by coupling between R′3GeX and RLi in an invertive process.

Chemischer InformationsdienstVolume 3, Issue 40 Preparative Inorganic Chemistry ChemInform Abstract: ORGANO-GERMANIUMVERBINDUNGEN 10. MITT. DIE STEREOCHEMIE DER SUBSTITUTION AM GERMANIUMATOM BEI EINIGEN RK. MIT NUCLEOPHILEN AGENTIEN C. EABORN, C. EABORNSearch for more papers by this authorR. E. E. HILL, R. E. E. HILLSearch for more papers by this authorP. SIMPSON, P. SIMPSONSearch for more papers by this author C. EABORN, C. EABORNSearch for more papers by this authorR. E. E. HILL, R. E. E. HILLSearch for more papers by this authorP. SIMPSON, P. SIMPSONSearch for more papers by this author First published: October 3, 1972 https://doi.org/10.1002/chin.197240376Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References C. EABORN, R. E. E. HILL, P. SIMPSON, ORGANO-GERMANIUMVERBINDUNGEN 10. MITT. DIE STEREOCHEMIE DER SUBSTITUTION AM GERMANIUMATOM BEI EINIGEN RK. MIT NUCLEOPHILEN AGENTIEN, J. Organomet. Chem., 1972, 37, 251. DOI: 10.1016/S0022-328X(00)96022-4; 10.1016/S0022-328X(00)96022-4 CASWeb of Science®Google Scholar Volume3, Issue40October 3, 1972 ReferencesRelatedInformation

Experiments in which alcohols are used to trap reactive intermediates suggest that the reactions between trialkyl phosphites and halogenoacetylenes, which yield ethynylphosphonates, proceed largely by initial displacement of acetylide ion from halogen by the nucleophilic phosphite. The mixed phosphate/phosphonate, diethyl 1-(diethoxyphosphono)ethyl phosphate, is one of the products formed when triethyl phosphite reacts with bromoethynylbenzene in hot acetic acid.

The synthesis of ethynylphosphonate esters in high yield is described. Di-isopropyl trimethylsilylethynylphosphonate, an intermediate in the synthesis of the di-isopropyl ester, undergoes a novel thermal rearrangement with loss of propene and migration of silicon from carbon to oxygen.

C. Eaborn, R. E. E. Hill and P. Simpson, Chem. Commun. (London), 1968, 1077 DOI: 10.1039/C19680001077

Recrystallisation of ethyl-1-naphthalyphenylgermyl (–)-menthoxide from pentane at –70° gave a diastereoisomer which, on reduction with lithium aluminium hydride in ether, gave the (+)-hydride, Et(1-C10H7)PhGeH, m. p. 31–32·5°, [α]D25+ 23·6°(c 5·5 in benzene). Crystallisation of ethyl-1-naphthylphenylgermyl (–)-1-phenylethoxide at ca.–15° gave crystals from which the optically impure (–)hydride, [α]D20–10·9°(c 13 in benzene) was obtained on reduction. The (+)-hydride was converted into the (–)-chloride by treatment with chlorine in carbon tetrachloride, and reduction of the chloride with lithium aluminium hydride gave the (–)-hydride. Only 7% of racemisation occurred in this Walden cycle, the existence of which shows that substitution at germanium can proceed by at least two distinct mechanisms, one involving predominant inversion and the other predominant retention of configuration. An unsuccessful attempt was made to repeat the work described in an earlier claim for resolution of a germanium compound, and that claim is critically considered.