Open AccessAllene Trifunctionalization via Amidyl Radical Cyclization and TEMPO Trapping
Author(s) -
Robert M. Ward,
Jennifer M. Schomaker
Publication year - 2021
Publication title -
journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.2
H-Index - 228
eISSN - 1520-6904
pISSN - 0022-3263
DOI - 10.1021/acs.joc.1c00675
Subject(s) - allene , chemistry , heteroatom , aryl radical , aryl , photochemistry , radical cyclization , radical ion , medicinal chemistry , catalysis , ring (chemistry) , organic chemistry , ion , alkyl
Radical-mediated trifunctionalizations of allenes are virtually unknown, in contrast to well-studied radical difunctionalizations of alkenes and alkynes. In this article, we describe a light-promoted reaction that transforms all three allene carbons to new carbon-heteroatom bonds in one pot with no expensive transition-metal catalyst. Formation of an electron donor-acceptor complex between an electron-deficient aryl and K 2 CO 3 , followed by photochemical generation of an amidyl radical and cyclization, yields a vinyl radical that can be trapped by TEMPO to ultimately furnish the product. Insights into the impact of the allene substitution pattern, radical source, and donor are presented, along with studies to unravel the mechanism of this unusual transformation.