One-shot photochemical synthesis of 5-(thiophen-3-yl)pyrano[2,3-c]chromen-2(3H)-ones from 3-propynyloxy-chromenones: a case of an intramolecular Paterno-Buchi reaction.
5-(Thiophen-3-yl)pyrano[2,3-c]chromen-2(3H)-ones (2), angular tricyclic compounds, were synthesized in significantly high yields through the photoinduced intramolecular coupling of the acetylenic group with the carbonyl centre in 3-(prop-2-ynyloxy)-2-(thiophen-3-yl)-4H-chromen-4-ones (1). This photoreaction is a case of an intramolecular Paterno-Buchi reaction and is unprecedented in 3-propynyloxy-chromenones. The structure of 2 has been determined by spectroscopic (FTIR, NMR and mass) and single crystal X-ray crystallographic studies.
Department of Chemistry, Kurukshetra University, Kurukshetra-136119, Haryana, India. rckamboj@hotmail.com.
Pooja
P
Jindal
Rimpy
R
Bhatia
Sadhika
S
Khullar
Sanjay K
SK
Mandal
Ramesh C
RC
Kamboj