time with the new resolving agent (R,R)- and (S,S)-2,3-di(phenylamino-carbonyl)tartaric acid (5c) (40–45% weight yields; >99% ee). The diamines (R)- or (S)-2a and 2b were converted with >98% stereochemical retention into the diiodides (R)- and (S)-3a and 3b and subsequently, without loss of optical purity, diphenylphosphinated to the known diphosphines (R)- and (S)-4a and 4b.
Construction of Axial Chirality and Silicon-Stereogenic Center via Rh-Catalyzed Asymmetric Ring-Opening of Silafluorenes
作者:Xiufen Bi、Jia Feng、Xiaoping Xue、Zhenhua Gu
DOI:10.1021/acs.orglett.1c00935
日期:2021.4.16
A rhodium-catalyzedenantioselectivering-opening/acylation of silafluorenes is reported. The newly developed bulky phosphoramidite ligand, in combination with methanol as the additive, enabled the reaction to create one axial chirality and one silicon-stereogenic center in a highly selective manner by only cleavage of one Si–C bond.
Hypervalent‐Iodine‐Mediated Carbon–Carbon Bond Cleavage and Dearomatization of 9
<i>H</i>
‐Fluoren‐9‐ols
作者:Ruixian Deng、Shuming Zhan、Chunyu Li、Zhenhua Gu
DOI:10.1002/anie.201913373
日期:2020.2.17
A transition-metal-free synthesis of spiro compounds from 9H-fluoren-9-ols mediated by hypervalent iodine is reported. In this reaction, an unprecedented β-carbon elimination of tertiary alkoxyliodine(III) to form new diaryliodonium salts is proposed. The obtained phenol intermediates undergo oxidative dearomatization to furnish a class of oxo-spiro compounds. This domino reaction significantly increases
(R)- and (S)-6,6′-dimethyl- and 6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyls: Versatile intermediates for the synthesis of atropisomeric diphosphine ligands
作者:Marco Cereghetti、Wolf Arnold、Emil A. Broger、Alain Rageot
DOI:10.1016/0040-4039(96)01090-8
日期:1996.7
Starting from enantiomerically pure 6,6′-dimethyl- or 6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyls (1a or 1b) a variety of atropisomeric diphosphine ligands of defined axial chirality are directly accessible in good yields: asymmetric diphosphines of type B and the corresponding diphosphines with one (type C) or two (type D) stereogenic phosphorus atoms. Pitfalls of the lithiation/phosphination reaction