Stereoselective synthesis of spirocyclic oxindoles based on a one-pot Ullmann coupling/Claisen rearrangement and its application to the synthesis of a hexahydropyrrolo[2,3-b]indole alkaloid
efficient and convenient approach to the synthesis of spirocyclicoxindoles from iodoindoles has been developed. The most striking feature of this approach is that the sequential intramolecular Ullmann coupling and Claisen rearrangement proceeds in a one-pot manner to afford 3-spiro-2-oxindoles in good yield with excellent diastereoselectivity. Application of this one-pot reaction to chiral non-racemic
A convergent synthesis of (4R,15R,16R,21S)-rollicosin (1) and (4R,15S,16S,21S)-rollicosin (2) was accomplished. Hydroxy lactone 6a and/or 6b were synthesized from 4-pentyn-1-ol, and α,β-unsaturated lactone 7 was synthesized from γ-lactone 8 and 5-hexen-1-ol. Inhibitory activity of these compounds was examined with bovine heart mitochondrial complex I.
A convergent stereoselective synthesis of (4R,15R,16R,21S)- and (4R,15S,16S,21S)-rollicosin and squamostolide was accomplished via a Pd-catalyzed cross-coupling reaction. The inhibitory activity of these compounds was examined with bovine heart mitochondrial NADH-ubiquinone oxidoreductase. These compounds showed a remarkably weak inhibitory activity compared to ordinary acetogenins such as bullatacin
Substrate control of diastereoselectivity in zirconium (II) mediated enyne cyclizations
作者:Brian L. Pagenkopf、Eric C. Lund、Tom Livinghouse
DOI:10.1016/0040-4020(94)01130-r
日期:1995.4
The reductive cyclization of an extensive series of chiral enynes by Cp2Zr(II) complexes has been examined. In most instances excellent substrate control of cyclization stereochemistry was observed.
Low-valenttitanium(II) complexes turned out to be suitable reagents in the promotion of alkyne/alkoxyallene coupling reactions in an intramolecular fashion. The conditions developed herein led to a broad range of highly functionalized cyclic adducts with excellent regioselectivities toward the central carbon of the alkoxyallene moiety. Good yields (up to 76%) were obtained over 19 examples. One-pot
低价钛( II )配合物被证明是促进分子内方式的炔烃/烷氧基丙二烯偶联反应的合适试剂。本文开发的条件产生了多种高度官能化的环状加合物,对烷氧基丙二烯部分的中心碳具有优异的区域选择性。 19 个实施例均获得了良好的产率(高达 76%)。通过亲电试剂捕获进行的一锅后期官能化也是可能的,并产生优异的非对映选择性(高达 95/5 dr)。