A Practical Entry to the Crambescidin Family of Guanidine Alkaloids. Enantioselective Total Syntheses of Ptilomycalin A, Crambescidin 657 and Its Methyl Ester (Neofolitispates 2), and Crambescidin 800
作者:D. Scott Coffey、Andrew I. McDonald、Larry E. Overman、Michael H. Rabinowitz、Paul A. Renhowe
DOI:10.1021/ja000234i
日期:2000.5.1
Among the most structurally remarkable guanidine natural products are the crambescidin/ptilomycalin A family of marine alkaloids. The evolution of a practical strategy for preparing pharmacologically significant crambescidin/ptilomycalin A alkaloids that lack oxidation at C13 is described. The first total syntheses of crambescidin 800 (2), crambescidin 657 (6), and neofolitispate 2 (7) are reported
A New Strategy for Efficient Synthesis of Medium and Large Ring Lactones without High Dilution or Slow Addition
作者:Wanxiang Zhao、Zigang Li、Jianwei Sun
DOI:10.1021/ja400883q
日期:2013.3.27
We have developed an efficient method for medium and large ring lactonesynthesis by a conceptually different ring-expansion strategy. The design of an unprecedented ring conjunction mode of oxetene, combined with the appropriate choice of a Lewis acid promoter and an additive, constitutes the key components of the new process. Enabled by this new approach, the reaction does not require high dilution
我们通过概念上不同的扩环策略开发了一种有效的中环和大环内酯合成方法。The design of an unprecedented ring conjunction mode of oxetene, combined with the appropriate choice of a Lewis acid promoter and an additive, constitutes the key components of the new process. 通过这种新方法,反应不需要高度稀释或缓慢添加。
Synthesis of medium-sized lactones from siloxy alkynes via ring expansion
作者:An Wu、Wanxiang Zhao、Jianwei Sun
DOI:10.1016/j.tet.2020.131163
日期:2020.12
topic in organic synthesis due to the disfavored kinetic and thermodynamic features. Herein we detail an efficient intermolecular process using siloxyalkynes as substrates and oxetene ring expansion as the key strategy. With extension to a new silyl-masked alkyne, this reaction now features a broad scope, high efficiency, and mild conditions.
Reaction of 2-methoxy-1,3-dioxane with grignard reagents: reagent-substrate complexation and stereoelectronic control.
作者:William F. Bailey、Allan A Croteau
DOI:10.1016/s0040-4039(01)90150-9
日期:——
The stereoelectronically controlledreaction of 2-methoxy-1,3-dioxane () with Grignard reagents does not follow the course suggested by the behavior of anancomeric models for the conformational isomers of . Treatment of with RMgX leads to the predominant formation of acid labile 3-(1′-methoxyalkoxy)-1-propanols, derived from endocyclic cleavage of the ring CO bond, and only minor amounts of the expected
Alkynyliodonium Salts in Organic Synthesis. Dihydrofuran Formation via a Formal Stevens Shift of a Carbon Substituent within a Disubstituted-Carbon Oxonium Ylide
作者:Ken S. Feldman、Michelle Laci Wrobleski
DOI:10.1021/jo0011080
日期:2000.12.1
and 1-pyranyl ethers of 1-hydroxybut-3-ynyl(phenyl)iodonium triflate triggers a sequence of reactions that ultimately delivers 2-substituted 3-p-toluenesulfonyldihydrofuran products in variable yields. A putative 1,2-group shift within an unsaturated oxonium ylide (Stevens rearrangement) accounts for the oxygen-to-carbon transfer of the ether substituent. Deuterium labeling studies clarify the mechanistic