2,2′‐Bifurylidene‐5,5′‐diones, Coumarins, 3a, 7a‐dihydro‐1H‐inden‐1‐ones, and 5H‐furo[3,2‐b]pyran‐5‐ones from propyne and carbon monoxide

Abstract

AbstractThe [Co2 (CO)8]‐catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re‐investigated. There are five major products: (E)‐3,4′‐dimethyl‐2,2′‐bifurylidene‐5,5′‐dione (4), 3,5,8‐trimethylcoumarin (8), 3a, 7a‐dihydro‐2,4,7,7a‐tetramethyl‐1H‐inden‐1‐one (9), 2,6‐dimethyl‐5H‐furo [3,2, ‐b]‐ pyran‐5‐one (11), and 2,7‐dimethyl‐5H‐furo 3,2‐b‐pyran‐5‐one (12); of these, only one, 4. had previously been recognized. In parallel experiments were obtained 2,6‐dipentyl‐5 H‐furo[3,2‐b]pyran‐5‐one (13), 2,7‐dipentyl–5H‐furo[3,2‐b]pyran‐5‐one (14), 3a, 7a‐dihydro‐2,4,7,7a‐tetrapentyl‐1H‐inden‐1‐one (15). And 3a, 7a‐dihydro‐2,4,6,7a‐tetrapentyl‐1H‐inden‐1‐one (16) from hept‐1‐yne, and two further types of products from two atypical 1‐alkynes: 3,6,9‐tri(tert‐butyl)‐1‐oxaspiro[4.4]nona‐3,6,8‐trien‐2‐one (20) from (tert‐butyl)acetylene and the exo‐dimer 21 of 2,5‐bis(trimethylsilyl)cyclopenta‐2,4‐dien‐1‐one (22) from (trimethylsilyl)acetylene. Compounds 11,12, and 20 were identified by X‐ray analysis.