Substituted Cyclopropenones¹

Synthesis and study of pseudoaromatic compounds. IX. A reevaluation of the question of aromatic character in tropones based on data derived from dipole moment measurements and CNDO/2[complete neglect of differential overlap/2] calculations

“…From the CND0/2 calculations on cyclopropenone, it is apparent that the bond lengths used are highly critical in determining the predicted charge densities. [36][37][38] However, regardless of the model used, the theory does predict a larger 7r polarization for this system than the remaining compounds considered in Table I. This result, which is in agreement with other recently reported SCF-MO calculations on cyclopropenone, 3 9 might have been anticipated intuitively since the electrostatic work necessary to achieve a cyclopropenium oxide structure would be considerably less than that necessary for the cycloheptatrienylium oxide structure.…”

The Chemistry of Phenylcyclobutenediones

“…The path followed leads via the pyridinium salt (14), from which (1s) can be liberated with acids. The reaction of (14) with (1Oa) yields the sulfide (18).…”

Development of a Catalytic Platform for Nucleophilic Substitution: Cyclopropenone‐Catalyzed Chlorodehydration of Alcohols

“…Cyclopropenones were first prepared by Breslow et al [6] and Volpin and co-workers [7] more than 50 years ago. These compounds have a number of useful qualities for applications in catalysis, which include straightforward preparation [8] in one or two steps from commercially available materials, and the ability to tune their physical and electronic properties ( Figure 1).…”