TiCl4 promoted reaction of aldehydes with 1,5-dienyl allylsilanes: addition accompanied by cyclization
摘要:
TiCl4 readily promotes the addition of 1,5-dienyl allylsilanes to aliphatic aldehydes with concomitant cyclization to afford 1,3-cis-disubstituted methylenecyclohexanes with remarkable stereoselectivity. The trimethylsilyl group exerts a strong activating and directing influence on the regioselectivity and stereoselectivity of this biomimetic cyclization. (C) 2000 Elsevier Science Ltd. All rights reserved.
A simple and efficient enantioselective synthesis of γ-cyclohomocitral, a key and versatile intermediate for the synthesis of some monocyclofarnesane terpenoids, is described. This features a highly sitoselective Sharpless asymmetric didydroxylation of a homomonoterpene diolefin. The first enantioselective synthesis of (−)-ancistrodial and (−)-pallescensone were accomplished. The (S)- configuration