Cyclopropenones structures

For a reveiw of cyclopropenones, see Eichcr Weber Top. Curr. Chem. Soc. 1975, 57, 1-109. For discussions of cyclopropenone structure, sec Shafer Schwcig Maier Sayrac Crandall Tetrahedron Lett. 1974, 1213 Tobcy. in Bcrgmann Pullman, Ref. 55, pp. 351-362 Greenberg Tomkins Dobrovolnv Ucbman J. Am. Chem. Soc. 1983, 105. 6855. 

Even rarer still are cyclopropenones. A recent report on a labile antibiotic penitricin (26) revealed it has the indicated cyclopropenone structure". Its mode of action is not yet known but it is doubtless an alkylating agent. 

The structural features and the spectroscopic characteristics of the thiirene dioxide system (22) are of special theoretical interest since, on the basis of analogy with cyclopropenone (23), it is a possible nonbenzenoid aromatic system with all the physical and chemical implications involved. Aromatic and/or conjugative effects, if any, require transmission through the d-orbitals of the sulfur atom. 

Library of Congress Cataloging in Publication Data. Main entry under title Cyclic compounds. (Topics in current chemistry 57). Bibliography p. Includes index. CONTENTS Eicher, T. and Weber, J. L. Structure and reactivity of cyclopropenones and triafulvenes. — Sargent, M. V. and Cresp, T. M. The higher annulenones. 1. Cyclic compounds—Addresses, essays, lectures. I. Eicher, Theophil, 1932- II. Series. 

Structure and Reactivity of Cyclopropenones and Triafulvenes Theophil Eicher and Josef L. Weber 1... 

The isolation of cyclopropenones and their undoubtedly increased stability compared to the less-strained saturated cyclopropanones might well be attributed to the validity of the above symbolism of aromatic cyclopropenium contribution to the ground state of 7. It should nevertheless be clear, that the information available on the electronic structure of cyclopropenones demands certain refinements of this very useful qualitative concept. 

The Wittig reaction of diphenyl cyclopropenone with the phosphorane 68 failed to give the methylene cyclopropene instead a hydrocarbon of probable structure 67 was obtained71. ... 

To a first approximation143) the dipole moment of cyclopropenone can be considered as an additive combination of the moments of structures a and b, which were estimated from group moments... 

Table 5. Structural data of cyclopropenone compared to cyclopropene (obtained from microwave spectra)...

The molecular structures of diphenyl cyclopropenone (anhydrous148 and as hy-drate13s 149 diphenylcyclopropene thione1501, 1,2-diphenyl-13S and 1,2-dimethyl-lsu 4,4-dicyano triafulvene, l,2-di-(p-tolyl)-4,4-di-(trifluoromethyl) triafulvenelslb), 5,6-diphenyl-1 S2 and 5,6-di-n-propyl-153 1,2,3,4-tetrachlorocalicene and 8-cyano-8-(diphenylcyclopropenyl)-heptafulvenylium tetrafluoroborate111 have been determined by X-ray analysis15 4). 

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