Synthesis of Unsymmetrical Azahelicenes by One-Pot Wittig–Heck and Photodehydrogenation SequenceGrant received from Science and Engineering Research Board (SERB), New Delhi No. SR/S1/OC-74/2012.
Received: 29 April 2017
Accepted after revision: 06 June 2017
14 July 2017 (eFirst)
We dedicate this paper to Professor Pradeep Kumar of National Chemical Laboratory (Pune, India) on the occasion of his 60th birthday
An efficient protocol for the synthesis of unsymmetrical azahelicenes has been developed. The bis-styryl-type substrates for regiospecific photodehydrogenative oxidative double cyclization to give helicenes were prepared by a one-pot Wittig–Heck sequence as well as a stepwise procedure. The derivatives were characterized by single-crystal X-ray diffraction analysis and fluorescence spectroscopy.