Conjugate reduction-initiated tandem cyclization of a chiral α,β,χ,ψ–unsaturated bisphosphine oxide

Conjugate reduction-initiated cyclization of a chiral α,β,χ,ψ-unsaturated bisphosphine oxide was developed by treating with lithium tri-siamylborohydride (LS-selectride®) as a reducing agent to afford efficiently and selectively a carbocycle bearing bisphosphine appendage.