(S,S)-N,N-Bis(-α-methylbenzyl)formamide is the first example of chiral formamides that function as Lewis base catalysis to effectively serve catalytic asymmetricsynthesis. The chiral formamide in combination with an additive, HMPA, catalyzes allylations of aliphatic aldehydes with allyl- and crotyltrichlorosilanes with high enantioselectivity (up to 98% ee). In the crotylations with (E)-crotyltrichlorosilane
Asymmetric synthesis via acetal templates. 9. Further studies of the allylation reaction. Preparation of (−)-dihydromyoporone
作者:William S. Johnson、Peter H. Crackett、John D. Elliott、Jacek J. Jagodzinski、Stephen D. Lindell、S. Natarajan
DOI:10.1016/0040-4039(84)80038-6
日期:——
A procedure has been developed for the high-yield coupling of chiral acetals 1 with allyltrimethylsilane (2, R′=H) as well as with methallyltrimethylsilane (2,R′=ME) to afford the hydroxy ethers 3 in which the new chiral center is formed highly enantioselectively. Homoallylic alcohols 4 of high ee are produced by removal of the chiral auxiliary.
Asymmetric synthesis via acetal templates. 3. On the stereochemistry observed in the cyclization of chiral acetals of polyolefinic aldehydes; formation of optically active homoallylic alcohols
作者:Paul A. Bartlett、William S. Johnson、John D. Elliott
DOI:10.1021/ja00345a082
日期:1983.4
Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision
This paper describes the first total synthesis of the proposed structure for aromin, an annonaceous acetogenin possessing an unusual bis-THF ring system, and its 4S,7R-isomer. The key steps involve an oxidative cyclization of a couple of terminal-diene alcohols and an intermolecular metathesis of an alkenyl tetrahydrofuran with an enone carrying a tetrahydrofuranyl lactone. The spectral data of both