Chemo enzymatic synthesis of Rengyol and Isorengyol
摘要:
Cyanohydrins 2 of O-protected 4-hydroxycyclohexanones 1 are excellent starting compounds for the synthesis of Isorengyol (I) and Rengyol (II). The cyano group of the O-benzyl derivative 2d is first converted into the corresponding aldehyde 4, which via Wittig olefination led to the vinyl Compound 6. Hydroboration of the trans-derivative (trans-6) leads, after debenzylation, to Isorengyol, whereas hydroboration and debenzylation of the cis-isomer (cis-6) gives Rengyol. With hydroxynitrile lyases (HNLs) as catalysts the stereoselective preparation of cis- as well as trans-cyanohydrin 2d is possible, which enables the selective preparation of Isorengyol or Rengyol, respectively. The trans-con figuration of Isorengyol and the cis-configuration of Rengyol were secured by X-ray crystal structure analysis. (c) 2006 Elsevier Ltd. All rights reserved.
Chemo enzymatic synthesis of Rengyol and Isorengyol
摘要:
Cyanohydrins 2 of O-protected 4-hydroxycyclohexanones 1 are excellent starting compounds for the synthesis of Isorengyol (I) and Rengyol (II). The cyano group of the O-benzyl derivative 2d is first converted into the corresponding aldehyde 4, which via Wittig olefination led to the vinyl Compound 6. Hydroboration of the trans-derivative (trans-6) leads, after debenzylation, to Isorengyol, whereas hydroboration and debenzylation of the cis-isomer (cis-6) gives Rengyol. With hydroxynitrile lyases (HNLs) as catalysts the stereoselective preparation of cis- as well as trans-cyanohydrin 2d is possible, which enables the selective preparation of Isorengyol or Rengyol, respectively. The trans-con figuration of Isorengyol and the cis-configuration of Rengyol were secured by X-ray crystal structure analysis. (c) 2006 Elsevier Ltd. All rights reserved.
Catalytic Radical–Polar Crossover Reactions of Allylic Alcohols
作者:Eric E. Touney、Nicholas J. Foy、Sergey V. Pronin
DOI:10.1021/jacs.8b12075
日期:2018.12.12
Radical-polarcrossover hydrofunctionalizations of tertiary allylic alcohols are described. Depending on the structure of the catalyst, corresponding epoxides or semipinacol rearrangement products are selectively obtained in good yields. Experimental evidence points to the participation of alkylcobalt complexes as electrophilic intermediates.