Silver(I)-Catalyzed Aminocyclization of 2,3-Butadienyl and 3,4-Pentadienyl Carbamates: An Efficient and Stereoselective Synthesis of 4-Vinyl-2-oxazolidinones and 4-Vinyltetrahydro-2<i>H</i>-1,3-oxazin-2-ones
作者:Masanari Kimura、Shuji Tanaka、Yoshinao Tamaru
DOI:10.1246/bcsj.68.1689
日期:1995.6
Silver(I) salts in combination with an appropriate base (mostly triethylamine) catalyzed the aminocyclization of N-substituted 2,3-butadienyl carbamates 1 (benzene, 50 °C) to provide 4-vinyl-2-oxazolidinones 2 in good yields. The stereoselectivity (trans-2/cis-2) ranged from 1.4 for C5-Me to >30 for C5-phenyl, isopropenyl, and t-butyl derivatives. 3,4-Pentadienyl tosylcarbamates 3, the one-carbon higher homologues of 1, underwent a similar cyclization to give 4-vinyltetrahydro-2H-1,3-oxazin-2-one 4 in synthetically useful yields and in higher trans selectivities than 1.
novel three-component reaction of alkadienol, CO2, and aryl or vinylic halide gives a vinyl group-substituted cyclic carbonate in one pot in the presence of a catalytic amount of a palladium complex. 2,3-Alkadienol affords five-membered ring carbonate in good yield, while 3,4-alkadienol effects the six-membered one successfully. 2,4-Alkadienol also takes part in this reaction to provide five-membered
Palladium-Catalyzed 1-Methylene-2-propenylation Reactions of Aryl Bromides with 3,4-Alkadien-1-ols via Carbon–Carbon Bond Cleavage for the Synthesis of 2-Aryl-1,3-butadiene Derivatives
method for the synthesis of 2-aryl-1,3-alkadienes has been developed. Treatment of aryl bromides with 3,4-alkadien-1-ols in the presence of a palladium catalyst results in 1 -methylene-2-propenyl group transfer to aryl bromides. Taking advantage of palladium-mediated retro-allylation as an sp 3 C-sp 3 C bondcleavage reaction, one can regard 3,4-alkadien-1-ols as 1-methylene-2-propenyl metal equivalents
Totalsynthesis of debromoflustramines B and E has been accomplished by using a platinum-catalyzed addition reaction of o-aminophenylboronic acid with the allene and an intramolecular carbamoylketene–alkene [2 + 2] cycloaddition for the construction of the basic carbon framework of the target alkaloids as the key steps.
Alcohols with a 2-(1,3-butadienyl) substituent are readily available from the Grignard reaction of chloroprene and are important as cross-conjugated triene equivalents. Some examples of double Diels–Alder reaction of the alcohols are first reported.