3017-68-3Relevant articles and documents
PALLADIUM-CATALYZED DIASTEREOSELECTIVE SYNTHESES OF (E)-1-TRIMETHYLSILYL-2-ALKENES, (E)-1-TRIMETHYLSILYL-1-ALKEN-3-YNES, (1E,5E)-1-TRIMETHYLSILYL-1,5-ALKADIEN-3-YNES, (1E,3Z)- AND (1E,3E)-1-TRIMETHYLSILYL-1,3-ALKADIENES
Andreini, Bianca Patrizia,Carpita, Adriano,Rossi, Renzo,Scamuzzi, Barbara
, p. 5621 - 5640 (2007/10/02)
On the basis of our observation that (E)-1-bromo-1-alkenes undergo preferentially stereospecific Pd-catalyzed cross-couplings with a variety of organometallics, in the presence of the corresponding (Z)-stereoisomers, efficient and convenient diastereoselective procedures have been developed to prepare nearly stereoisomerically pure (E)-1-trimethylsilyl-2-alkenes (4), (E)-1-trimethylsilyl-1-alken-3-ynes (5), (1E,5E)-1-trimethylsilyl-1,5-alkadien-3-ynes (6), and (1E,3E)-1-trimethylsilyl-1,3-alkadienes (8) from stereoisomeric mixtures of alkenyl bromides.Compounds 5 have been stereoselectively converted into (1E,3Z)-1-trimethylsilyl-1,3-dienes (7) by selective hydrometallations, followed by hydrolysis.Some synthetic applications of compounds 5-8 have been also examined.
Copper(I)-Mediated Synthesis of cis-Isoprenoids. Models for Natural Rubber
Parr, William J. E.
, p. 4101 - 4130 (2007/10/02)
Two copper(I)-mediated routes for the preparation of all-cis-2,6,10-trimethyl-2,6,10-dodecatriene are investigated.Reaction of the Grignard reagent derived from 1-bromo-4-methylpent-3-ene with CuBr, and then with excess propyne, gave a vinylcopper intermediate which could be alkylated with 1-iodo-3-methylpent-3-ene, to afford the required triene stereospecifically cis- in 28percent yield.Iodination of the same intermediate and subsequent conversion to 1-bromo-4,8-dimethyl-3,7-nonadiene is shown to occur with retention of configuration, so allowing the iterative construction of cis-isoprenoids.This vinylcopper-based route is shown to be also applicable to the synthesis of larger cis-isoprenoids.In contrast, the CuI-modified coupling reaction of the Grignard reagent from 1-chloro-2-methylbut-2-ene with neryl chloride gave a mixture of triene isomers.
