Etudes sur les matières végétales volatiles. XVIII. Sur l'absorption de la pipériténone et de cétones voisines dans l'ultra‐violet

Abstract

A l'isopip6rit6none que nous n'avons encore pu isoler correspondent la y-atlantone et la sylvbcarvone de Wallach*). En outre, il semble que la cyclisation du citral ait livr6 l'isopip6ritho1, c'est du moins l'hypothkse qui a &ti. formu1i.e par Zritschel et Sch1121d15) _ , 1) XVIIe Communication: Helv. 25, 984 (1942:.

Photochemical Reactions of α,β-Unsaturated Carbonyl Compounds with Olefins

“…If one postulates that the diradical I is first formed in the reaction of 17 with isobutylene, the preferential formation of 18 is then understandable, for (1) the oxygen is inaccessible for direct coupling, (2) hydrogen abstraction involving a six-membered ring transition state is probably favored over the coupling of two tertiary radicals to form a cyclobutane,28 and (3) the preferred (25) N. S. Bhacca and D. H. Williams, "Applications of Nmr Spectroscopy in Organic Chemistry," Holden-Day, Inc., San Francisco, Calif., 1964, pp 47-49. (26) The absorption for the axial -proton in 19 should also be broader than that of the corresponding equatorial a-proton in 18 (ref 25, pp [49][50][51][52].…”