Stereochemical control in the ester enolate Claisen rearrangement. 2. Chairlike vs boatlike transition-state selection
作者:Robert E. Ireland、Peter Wipf、Jia Ning Xiang
DOI:10.1021/jo00011a023
日期:1991.5
The preference for chair- and boatlike transition-state geometries in the ester enolate Claisen rearrangement of straight chain, carbocyclic, and heterocyclic propanoates was investigated. A novel stereoelectronic effect in pyranoid and furanoid glycal systems leads to a significant relative stabilization of the boatlike vs the chairlike TS double-ended-dagger. The preferred transition state in six- and five-membered carbocyclic systems is highly dependent on steric factors, as the energy difference between chair- and boatlike TS double-ended-dagger tends to be small. With straight-chain substrates, a significant contribution of the boatlike TS double-ended-dagger to the rearrangement product mixture is only expected in bis-donor substituted allylic esters.
Evaluation of the Claisen rearrangement of 2-cyclohexenols for the stereoselective construction of a terpene synthon
作者:Paul A. Bartlett、Cheryl F. Pizzo
DOI:10.1021/jo00332a027
日期:1981.9
Stereoselective Synthesis of the A,E-Ring Bicyclic Core of Calyciphylline B-Type Alkaloids
作者:Balagani Satish Kumar、Sadagopan Raghavan
DOI:10.1055/s-0039-1690721
日期:2019.12
A stereoselectivesynthesis of the bicyclic unit constituting the A and E rings of calyciphylline B-type alkaloids is disclosed. The propionate ester of (1R)-cyclohex-2-en-1-ol, obtained by enzymatic resolution, is subjected to an Ireland–Claisen rearrangement. Subsequent reduction of the acid, Mitsunobu reaction to introduce a nitrogen functionality, oxidative cleavage to a dialdehyde, and intramolecular
公开了构成花椰菜碱 B 型生物碱的 A 和 E 环的双环单元的立体选择性合成。通过酶促拆分获得的 (1R)-cyclohex-2-en-1-ol 的丙酸酯进行爱尔兰-克莱森重排。随后的酸还原、Mitsunobu 反应引入氮官能团、氧化裂解为二醛,以及分子内醛醇和氮杂-迈克尔反应提供双环亚基。