bicyclic core structures with up to three stereocenters within a single step. Herein, this concept is combined with the chemistry of chiral Brønsted acid bound ortho-quinonemethideimines to generate a range of interesting fused tetrahydroquinolines in a diastereo- and enantioselective manner.
Four newsigmatropicsequences triggered by the regiocontrolled [2,3]-Wittig rearrangement of unsymmetrical bis-allylic ethers (1) to the l,5-dien-3-ols (2) arc described, which provide unique, regiocontrolled methods for the synthesis of a wide variety of unsaturatedcarbonylcompounds possessing interesting molecular frameworks. The newly developed sequences include the [2,3]-Wittig-Claisen, the
Intramolecular [4+2]-cycloadditions of nitroalkenes with olefins. 2
作者:Scott E. Denmark、Young-Choon Moon、Christopher J. Cramer、Michael S. Dappen、C.B.W. Senanayake
DOI:10.1016/s0040-4020(01)89054-2
日期:1990.1
The intramolecular [4+2]-cycloadditions of di- and trisubstituted nitroalkenes with unactivated olefins are described. The cycloadditions proceed readily at low temperatures in the presence of SnCl4. The reactions are shown to be stereospecific in the preservation of dienophile configuration in the product. The configuration of the heterodiene controls the stereochemistry of the ring fusion but the
Diastereoselectivity in the intramolecular cycloaddition reactions of nitrones derived from 5-alkenals and chiral hydroxylamines
作者:S.W. Baldwin、R.B. McFadyen、J. Aubé、J.D. Wilson
DOI:10.1016/0040-4039(91)80004-p
日期:1991.1
Intramolecularcycloaddition of the nitrones derivedfrom a series of 5-alkenals and α-methylbenzyl hydroxylamine leads to mixtures of diastereomeric products in the range of 1.7/1 to 16/1.
Synthesis of Tetrahydropyran/Tetrahydrofuran‐Containing Macrolides by Palladium‐Catalyzed Alkoxycarbonylative Macrolactonizations
作者:Yu Bai、Dexter C. Davis、Mingji Dai
DOI:10.1002/anie.201403006
日期:2014.6.16
A novel Pd‐catalyzed cascade alkoxycarbonylativemacrolactonization to construct tetrahydropyran/tetrahydrofuran‐containing bridged macrolactones in one step from alkendiols is described. Products with various ring sizes and substituents were obtained. Challenging macrolactones involving tertiary alcohols were synthesized smoothly as well. Mechanistically, experimental evidence to support a trans‐oxypalladation