Highly Enantioselective Syntheses of Homopropargylic Alcohols and Dihydrofurans Catalyzed by a Bis(oxazolinyl)pyridine−Scandium Triflate Complex
作者:David A. Evans、Zachary K. Sweeney、Tomislav Rovis、Jason S. Tedrow
DOI:10.1021/ja011983i
日期:2001.12.1
Lewisacid promoted reactions of allylsilanes and allenylsilanes provide access to important building blocks for natural product synthesis. 1 For example, trimethylsilylallenes function as propargylic anion equivalents in aldehydeadditionreactions (eq 1, Path A).2 If the silicon center is sterically congested, the normal addition pathway is suppressed and functionalized dihydrofurans are produced
Stereoselective synthesis of both geometric isomers of γ-(trimethylsilyl)allylboranes and the diastereoselective condensations with aldehydes
作者:Yu Gui Gu、Kung K. Wang
DOI:10.1016/0040-4039(91)80678-y
日期:1991.6
Hydroboration of allenylsilanes 1 produces the Z isomers 10 as the kinetic product, leading to hydroxyallylsilanes 15 after condensation with hexanal, whereas the E isomers 4 and 12 are thermodynamically more stable, affording 9 predominantly.
Lewis acid-catalyzed three-component condensation reactions of aldehydes, alkoxysilanes, and allenylsilanes: synthesis of α-propargyl ethers
作者:Lui Niimi、Shuichi Hiraoka、Tsutomu Yokozawa
DOI:10.1016/s0040-4020(01)01145-0
日期:2002.1
Lewis acid-catalyzed reaction of acetals with allenylsilanes and the three-component reactions of aldehydes, alkoxysilanes, and allenylsilanes are described. Both reactions are strongly dependent on the substituent at the α-position of allenylsilanes. Allenylsilanes having bulky substituents such as the tert-butyl and isopropyl groups result in the corresponding α-propargyl ethers in high yields, whereas
A highly regio‐ and stereoselective copper‐catalyzed borylcupration of 1,2‐allenylsilanes affords an unexpected regioreversed allylic boronate bearing an extra C−Si bond at the 3‐position, with a thermodynamically disfavored Z geometry. Such stereodefined allylic boronates containing an extra alkenyl silane moiety are very useful organodimetallic reagents for organic synthesis.
A new practical route for the first total synthesis of (+)-homopumiliotoxin 223G is described, in which the palladium-catalyzedcarbonylation of the vinyl iodide, leading to efficient construction of the quinolizidine nucleus incorporating the (Z)-alkylidene side chain, is the key strategic element. Another key feature of this synthesis involves the Lewis acid-induced chelation-controlled propargylation