General facile synthesis of 2,5-diarylheteropentalenes
摘要:
Palladium-catalyzed cross-coupling reactions of various heteropentalene derivatives were systematically studied. A general three-step synthesis of 2,5-diarylheteropentalenes involving two Suzuki or Negishi couplings and a regiospecific bromination was developed. Nonsymmetrical 2,5-diaryl-furans, thiophenes, pyrroles, 1,3-thiazoles, 1,3-oxazoles, 1,3,4-thiadiazoles, and 1,3,4-oxadiazoles were prepared in 31-67% isolated yield (three steps). (C) 2004 Elsevier Ltd. All rights reserved.
The direct C-H heteroarylation of thiophenes, promoted by rigid α-diimine palladium complexes is described. This approach exhibits broad substrate scopes with functional group tolerant, and proceeds with the formation of regioselective products.
[EN] IMPROVED PHOTOCHEMICAL SYNTHESIS OF VITAMIN D3 USING SENSITIZERS<br/>[FR] SYNTHÈSE PHOTOCHIMIQUE AMÉLIORÉE DE LA VITAMINE D3 À L'AIDE DE SENSIBILISATEURS
申请人:FERMENTA BIOTECH LTD
公开号:WO2020230169A1
公开(公告)日:2020-11-19
The present invention discloses an improved photochemical synthesis of vitamin D3 from 7-dehydrocholesterol alone or in combination with sterol precursors in presence of the photosensitizer of Formula I in high yield and with reduced levels of impurities.