ALKENES AS ALKYNE EQUIVALENTS IN RADICAL CASCADES TERMINATED BY FRAGMENTATIONS

摘要

Disclosed are methods for rerouting radical cascade cyclizations by using alkenes as alkyne equivalents. The reaction sequence is initiated by a novel 1,2 stannyl shift which achieves chemo- and regioselectivity in the process. The radical “hopping” leads to the formation of the radical center necessary for the sequence of selective cyclizations and fragmentations to follow. In the last step of the cascade, the elimination of a rationally designed radical leaving group via β-C—C bond scission aromatizes the product without the need for external oxidant. The Bu3Sn moiety, which is installed during the reaction sequence, allows further functionalization of the product via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.

主权项

1. A method of synthesizing a Sn-functionalized aromatic compound comprising a fused aromatic ring system, the method comprising contacting a stannane compound and a reactant compound having the following structure (I): wherein: each of Ra, Rb, Rc, and Rd are independently carbon or nitrogen; each R1 R2, R3, and R4 independently comprises hydrogen, halogen, cyano, amino, alkyl, alkoxy, alkenyl, alkynyl, aryl, or any two adjacent R1 R2, R3, and R4 together form a fused aromatic ring system; X is selected from the group consisting of hydroxyl, alkyl, alkoxy, cycloalkyl, heterocyclic, amino, aryl, heteroaryl, and benzyl; and Ar comprises aryl or heteroaryl, which may be unsubstituted or substituted.