Chiral boronates—versatile reagents in asymmetric synthesis
作者:Sabine Thormeier、Bertrand Carboni、Dieter E Kaufmann
DOI:10.1016/s0022-328x(02)01323-2
日期:2002.9
The new, axially chiral borates 2, 9, and 11 and boronates 3–6 and 12 are synthesized in good yields. They are representatives of three different structural types. The bicyclic borates 2 and 9 are homochiral propeller compounds; their exclusive formation is used to increase the enantiomerical purity of 1. Especially the borates are efficient Lewis acidic catalysts for stereoselective Diels–Alder reactions
[GRAPHICS]Dispiro[2.1,3.2]decane, the first of the five possible dispirodecanes constituted from one three-membered, one four-membered, and one five-membered ring to be synthesized, has been prepared efficiently in four steps from methylenecyclopropane and again in five steps from methylenecyclobutane.