Studies in the Synthesis of Coumarino-α-pyrones and Furocoumarins Part XVII. Synthesis of Psoralene Derivatives

Chemistry Department, Faculty of Science, M.S. University of Baroda, Baroda

Manuscript received 10 May 1972; accepted 30 April 1974

Pechmann condensation of 2-methyl resorcinol with ethyl cyclopentanone-2-carboxylate and ethyl cyclohexanone-2-carboxylate gave 7-hyiroxy-8-methyl-3,4 cyclopentenocoumarin and 7-hydroxy-8-methyl-3,4-cyclohexenocoumarin respectively. These on allylation followed by Claisen rearrangement gave the corresponding 6-allyl derivative, which when treated with osmium tetro­xide and potassium periodate gave the corresponding 6-(2'-oxoethyl) derivatives. These were cyclised to (IIIa) and (V) respectively. 6-Allyl derivatives were also cyclised with conc. sulphuric acid to give the corresponding 2,3-dihydrofurocournarin derivatives, which on dehydrogenation gave (IIIb) and (VII).