benzosiloles is accomplished by 2-fold metalation of benzo[b]thiophenes substituted at C3 with ortho-brominated aryl groups followed by electrophilic substitution with dichlorosilanes. The method relies on the innate acidity of the C(sp2)–H bond at C2 of benzo[b]thiophenes and the halogen–metal exchange of the proximal C(sp2)–Br bond. The related indole- and benzofuran-annulated systems are also accessible
各种噻吩稠合的苯并甲酚的直接组装是通过在C3处用邻溴化的芳基进行2倍苯并[ b ]噻吩的2倍金属化,然后用二氯硅烷进行亲电取代来实现的。该方法依赖于苯并[ b ]噻吩的C2处C(sp 2)-H键的固有酸度和近端C(sp 2)-Br键的卤素-金属交换。也可以使用相关的吲哚和苯并呋喃环化的系统,但是这些硅烷的化学稳定性较差。还包括噻吩稠合的苯并germol的例子。
A New Modular Class of Easily Accessible, Inexpensive, and Efficient Chiral Diphosphine Ligands for Homogeneous Stereoselective Catalysis
The syntheses of a wide range of novel C 1-symmetric chelating diphosphanes with stereogenic axes are reported. These ligands feature identical or different phosphanyl groups supported on diverse atropisomeric templates based on the interconnection of five-membered heteroaromatic and six-membered carbocyclic rings. Easy synthetic accessibility, independent tunability of the electronic and steric properties of the two phosphane donors, the low cost and the good stereoselection ability of some of them obtained in an enantiopure state are the main advantageous features of this class of ligands.