The reaction of sodium diselenide with opticallyactive alkyl tosylates or chlorides is found to be a useful method for the synthesis of opticallyactive dialkyl diselenides. Opticallyactive monoterpene diselenides derived from menthane, carane, pinane, and bornane systems have been obtained. The influence of the terpene fragment of the obtained diselenides on the diastereomeric excess of the methoxyselenylation
The bicyclic tertiary amine 1,4-diazabicyclo[2.2.2]octane (DABCO) is a promising substitute not only for the widely used but hazardous and hygroscopic base pyridine in the syntheses of alkyl tosylates 3 but also for triethylamine in the preparation of alkyl sulfenates 4 from sterically hindered alcohols 2. In several provided examples the substrates 2 were completely converted into the desired products, e.g. the respective tosylates 3, which minimized subsequent separation processes. The current protocol points, in a number of cases, to nonchlorinated solvents as good alternatives to chloroform or dichloromethane and offers a workup procedure for a larger scale reaction which relies on the removal of the side products by filtration instead of the traditional extraction method using several aqueous washings.
Synthesis of Chiral Sulfinic Acids: Sodium(1<i>S-exo</i>)-2-Bornanesulfinate
作者:José M. Blanco、Olga Caamaño、Ana Eirín、Franco Fernández、Lucia Medina
DOI:10.1055/s-1990-26948
日期:——
A convenient synthesis of the title compound from (-)-borneol, as a model applicable to that of other chiral, sensitive sulfinic acids, via the nucleophilic cleavage of the corresponding phthalimidomethyl sulfone, is described.