An effective strategy for acyclic synthesis via iterative rearrangement of allylic glycolates. Synthesis of a pine sawfly pheromone
作者:James Kallmerten、Michael Balestra
DOI:10.1021/jo00364a058
日期:1986.7
Synthesis of enantioenriched .alpha.-hydroxy-.alpha.-allenylacetic acids by [2,3] Wittig rearrangement of .alpha.-(propargyloxy)acetates
作者:James A. Marshall、Xiao Jun Wang
DOI:10.1021/jo00016a020
日期:1991.8
Optically active (R)-(propargyloxy)acetic esters 5, available in ca. 90% ee through reduction of alkynones 2 with Chirald-LiAlH4 followed by alkylation with chloroacetic acid and esterification with CH2N2, undergo highly stereoselective [2,3] rearrangement upon treatment with LDA in THF at -78-degrees-C followed by Cp2ZrCl2 to afford alpha-(S)-hydroxy-beta-(R)-allenic esters 7 with complete transfer of chirality and > 90% diastereoselectivity. Upon treatment with TESOTf in Et3N the (R)-(propargyloxy) acetic esters 5 afford the diastereomeric alpha-(R)-hydroxy-beta-(R)-allenic esters 8 stereoselectively. Both hydroxy esters 7 and 8 cyclize stereospecifically to trans- and cis-2,5-dihydrofurans 13-15 and 17-19 upon treatment with AgNO3-CaCO3, PhSeCl, or NBS.
US4784797A
申请人:——
公开号:US4784797A
公开(公告)日:1988-11-15
US4784796A
申请人:——
公开号:US4784796A
公开(公告)日:1988-11-15
Stereoselective Synthesis of Tertiary Ethers through Geometric Control of Highly Substituted Oxocarbenium Ions
作者:Lei Liu、Paul E. Floreancig
DOI:10.1002/anie.201002281
日期:2010.8.9
Fully substituted, fully controlled! The geometries of 1,1‐disubstituted oxocarbeniumions and the conformations of oxocarbeniumions that contain a tertiary stereocenter can be predicted based on simple models. These models have been applied to highlystereoselective syntheses of tetrahydropyran derivatives that contain tertiaryethers (see scheme; RL, RS, and RN represent large, small, and nucleophilic
全面换人,全面控制!1,1-二取代的氧碳鎓离子的几何形状和包含叔立构中心的氧碳鎓离子的构象可以基于简单的模型来预测。这些模型已应用于含有叔醚的四氢吡喃衍生物的高度立体选择性合成(参见方案;R L、RS和 R N分别代表大基团、小基团和亲核基团)。