Studies on furan derivatives IV. A simple preparation of α‐substituted β‐(5‐nitro‐2‐furyl)ethynyls from α‐substituted β‐(5‐nitro‐2‐furyl)vinylamines

α‐Substituted β‐(5‐nitro‐2‐furyl)ethynyls were conveniently prepared by the deamination of α‐substituted β‐(5‐nitro‐2‐furyl)vinylamines. Also the application of this reaction toward α,β ‐bis( p ‐nitrophenyl)vinylamine was examined and afforded α,β ‐bis( p ‐nitrophenyl)ethynyl as the main product.