Origins of Endo Selectivity in Diels-Alder Reactions of Cyclic Allene Dienophiles.

ABSTRACT: Strained cyclic allenes, first discovered in 1966 by Wittig and co-workers, have recently emerged as valuable synthetic building blocks. Previous experimental investigations, and computations reported here, demonstrate that the Diels-Alder reactions of furans and pyrroles with 1,2-cyclohexadiene and oxa- and azaheterocyclic analogs proceed with endo selectivity. This endo selectivity gives the adduct with the allylic saturated carbon of the cyclic allene endo to the diene carbons. The selectivity is very general and useful in synthetic applications. Our computational study establishes the origins of this endo selectivity. We analyze the helical frontier molecular orbitals of strained cyclic allenes and show how secondary orbital and electrostatic effects influence stereoselectivity. The LU

SUBMITTER: Ramirez M 

PROVIDER: S-EPMC8217342 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature