Dialkylaluminum <i>N</i>,<i>O</i>-Dimethylhydroxylamine Complex as a Reagent to Mask Reactive Carbonyl Groups in Situ from Nucleophiles
作者:Francis J. Barrios、Xuechao Zhang、David A. Colby
DOI:10.1021/ol102495v
日期:2010.12.3
mask carbonylgroups in situ from nucleophilic addition by organolithiums, Grignard reagents, and borohydrides. The utility of this process by selectively adding nucleophiles into carbonylgroups on a variety of structures as well as distinguishing between carbonylgroups on a sensitive natural product is demonstrated. 1H NMR analysis supports the in situ masking of the more reactivecarbonyl group
N,O-二甲基羟胺的铝络合物是有效掩盖羰基的有效试剂,可防止有机锂,格氏试剂和硼氢化物的亲核加成。通过选择性地将亲核试剂添加到各种结构的羰基中以及区分敏感的天然产物上的羰基,证明了该方法的实用性。1 H NMR分析支持对反应性更高的羰基进行原位掩蔽。
Pd-Catalyzed Formal [2 + 2]-Retrocyclization of Cyclobutanols via 2-Fold Csp<sup>3</sup>–Csp<sup>3</sup> Bond Cleavage
describe the unexpected 2-fold Csp3–Csp3 bond cleavage suffered by cyclobutanols in the presence of a catalytic amount of Pd(OAc)2 and promoted by the bulky biaryl JohnPhos ligand. Overall, the sequential cleavage of a strained and an unstrained Csp3–Csp3 bond leads to the formal [2 + 2]-retrocyclization products, namely, styrene and acetophenone derivatives. This procedure might enable the use of cyclobutanols