Caught in the act: N‐Heterocyclic carbenecopper(I) complexes (1; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) serve as an excellent catalyst for the carboxylation of alkylboranes (2; R=alkyl) with CO2 to afford a variety of functionalized carboxylicacids (3) in high yields. A novel copper methoxide/alkylborane adduct (A) and its subsequent CO2 insertion product (B) have been isolated and
参与其中:N-杂环卡宾铜(I)络合物(1 ; IPr = 1,3-双(2,6-二异丙基苯基)咪唑-2-亚烷基)是烷基硼烷羧化的极佳催化剂(2 ; R =烷基)与CO 2一起以高收率提供各种官能化的羧酸(3)。一种新型的甲醇铜/烷基硼烷加合物(A)及其随后的CO 2插入产物(B)已被分离出来,并被证明是真正的活性催化剂。
Remote functionalization on the steroid β-face: Attack on an angular methyl group, and into the sidechain
作者:Ronald Breslow、Uday Maitra、Dennis Heyer
DOI:10.1016/s0040-4039(01)91539-4
日期:——
Benzophenonealkanoate esters of 6-β-cholestanes insert photolytically into C-15, C-16, and the C-18 methyl, or into C-23 and C-25 of the sidechain, depending on the length of the attaching chain.