Deprotection and saponification of the latter led to aminodeoxyerythrose and to aminodeoxyribose derivatives as an equilibrium of pyrrolidinose equivalents, i.e., hemiaminals 14a, b, imines 14′a, b, and dimers 14″a,b, respectively (Scheme 3). Hydrocyanic acid addition to 11a, b led ultimately to the proline derivatives 16a, b (Scheme 2). Compound 11b proved to be an inhibitor of syncytium formation in AIDS-infected
Rate Enhancement in Ethanolic Aqueous Buffer. The Diels-Alder Reaction
作者:Michael B. Smith、Joseph N. Fay、Young Chan Son
DOI:10.1246/cl.1992.2451
日期:1992.12
We have observed a 2.5-3-fold increase in the rate of Diels-Alder reactions when done in aqueous ethanol, where the aqueous solution was prepared with a pH 7 buffer. This is a simple, inexpensive and convenient method for modest acceleration of the Diels-Alder reaction, in addition to the rate increase normally observed in aqueous media.
Efficient Enantio-, Diastereo, <i>E</i>/<i>Z</i>-, and Site-Selective Nickel-Catalyzed Fragment Couplings of Aldehydes, Dienes, and Organoborons
作者:Justin S. Marcum、Simon J. Meek
DOI:10.1021/jacs.2c08742
日期:2022.10.26
The enantioselective synthesis of bis-homoallylic alcohols through nickel-catalyzed three-component fragment couplings of simple aldehydes, dienes, and aryl organoborons is disclosed. The reactions proceed through diene dicarbofunctionalization that concurrently forms two C–C bonds and two stereogenic centers. The transformations are promoted by a 5.0 mol % loading of a readily accessible chiral phosphine–nickel