A new [ABCD → ABCDE] cycloaddition strategy for the approach to Yohimbe alkaloids : Stereoselective synthesis of (±)-3-epi-allo-yohimbone
摘要:
Diels-Alder cycloaddition between lactam-sulfone 9 and diene 10 led to adducts 11 + 12 (30 : 1, respectively). Compound 11 has been converted in 4 steps into (+/-)-3-epi-allo-yohimbone 16.
A new [ABCD → ABCDE] cycloaddition strategy for the approach to Yohimbe alkaloids : Stereoselective synthesis of (±)-3-epi-allo-yohimbone
摘要:
Diels-Alder cycloaddition between lactam-sulfone 9 and diene 10 led to adducts 11 + 12 (30 : 1, respectively). Compound 11 has been converted in 4 steps into (+/-)-3-epi-allo-yohimbone 16.
Stereocontrolled Annulations of Indolo[2,3-<i>a</i>]quinolizidine-Derived Lactams with a Silylated Nazarov Reagent: Access to Allo and Epiallo Yohimbine-Type Derivatives
作者:Federica Arioli、Maria Pérez、Celeste Are、Carolina Estarellas、F. Javier Luque、Joan Bosch、Mercedes Amat
DOI:10.1002/chem.201501912
日期:2015.9.14
The facial selectivity of double Michael addition reactions of the silylated Nazarov reagent 4 to unsaturated indolo[2,3‐a]quinolizidine lactams 3 has been studied. Pentacyclic 3‐H/15‐H trans adducts 5 are generated from Nind‐unsubstituted lactams, but the corresponding cis isomers 6 are formed when the indole nitrogen has a tert‐butyloxycarbonyl (Boc) substituent. This reversal in the facial selectivity
已研究了甲硅烷基化的Nazarov试剂4对不饱和吲哚[2,3- a ]喹诺唑烷内酰胺3的两次迈克尔加成反应的面部选择性。五环3-H / 15-H反式加合物5个从产生Ñ IND -未被取代的内酰胺,但相应的顺式的异构体6时的吲哚氮具有形成叔‐丁氧羰基(Boc)取代基。通过理论计算已经合理地消除了环形表面选择性的这种逆转,这表明在立体电子控制下的初始亲核攻击受到了庞大Boc基团的阻碍。五环Nazarov衍生的加合物的合成有用性通过将其转化为异源和Epiallo育亨宾型靶标而得到证明。