Suggested is a fragrance mixture comprising specific esters of (−)-carveol and/or (−)-dihydro-carveol.
建议使用由 (-)- 香芹醇和/或 (-)- 二氢香芹醇的特定酯类组成的香味混合物。
Stereochemical control in the ester enolate Claisen rearrangement. 1. Stereoselectivity in silyl ketene acetal formation
作者:Robert E. Ireland、Peter Wipf、Joseph D. Armstrong
DOI:10.1021/jo00002a030
日期:1991.1
Methods for the stereoselective deprotonation and silylation of esters were systematically investigated. A kinetically controlled enolization in combination with a kinetic resolution process accounts for the selective formation of (E)- and (Z)-silyl ketene acetals in THF and THF/dipolar solvent systems with bases such as LDA, LHMDS, and KHMDS. A thermodynamic equilibration mechanism seems to be of minor significance with ester enolates. Improved reaction conditions were exemplified in a highly stereoselective Claisen rearrangement in THF/45% DMPU.
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.
IRELAND, ROBERT E.;WIPF, PETER;ARMSTRONG, JOSEPH D. III, J. ORG. CHEM., 56,(1991) N, C. 650-657
作者:IRELAND, ROBERT E.、WIPF, PETER、ARMSTRONG, JOSEPH D. III
DOI:——
日期:——
IRELAND, ROBERT E.;WIPF, PETER;XIANG, JIA-NING, J. ORG. CHEM. , 56,(1991) N1, C. 3572-3582