Thermal Reactions of Epoxyenones and Epoxydienes in the Ionone Series

Abstract

On flash vacuum thermolysis at temperatures between 390 and 585", the epoxyenones 1-9 and the epoxydienes 10-12 undergo various types of reactions involving C-C and/or C-0 bond cleavage in the oxirane ring. Thus, the compounds 1,4-9,11, and 12 were transformed to the divinyl ethers 13,20,21,24,25,29, and 38 by a reversible [I ,5] homosigmatropic H-shift. On thermolysis of the epoxides 1-12, several products formed via carbonyl-ylide intermediates were also isolated. The extent of the formation of ylide products is clearly related to the conjugating ability of the functional groups neighboring the oxirane. Thus, the epoxides 3, 5, and 7-10, bearing a C(3)=C (4) bond, a 5-0x0 function, a 3,4-epoxy or a 3,4-methano group, preferentially underwent reactions via a carbonylylide intermediate. As a further reaction pathway, the epoxides 1-12 undergo cleavage of the C-0 bonds of the oxirane, which, however, is presumably an acid-catalyzed rather than a thermal reaction.

Photochemical reactions of nitrile compounds. Part 2. Photochemistry of an α,β-unsaturated γ,δ-epoxy nitrile and an γ,δ-cyclopropyl nitrile

“…5, 25.8, and 30.3 (3 x q, 3 x Me), 35.1 (s, C-2), 40.9 (2 x t, C-3 and C-5), 69.2 (d, C-7), 90.4 (s, C-6), 112.1 (d, C-8), 118.7 (s, CN), and 158.8 (s, C-1); m/z, 191 ( M ' ) and 43 ( M + -148, 100%). penonitrile (14) had b.p. 130 "C at 0.07 mmHg; h,,,.…”

“…respectively due to the methyl ketone or the methyl hydrazone side-chain, and double doublets at 6 6.55 (J 16 and 9 Hz), 6 6.53 (J 16.6 and 11.2 Hz), and a triplet at 6 6.32 (J 1 1 Hz) due to 3-H. The configuration of compound (14) was determined by its methanolysis to the known methyl ester (28) 4 (56",), in which the methyl ketone and the enenitrile sidechains are cis-disposed. Thus, the configuration of the sidechains in (15) is trans.…”

“…The mixture (15) and (19) (8:2) could not be separated. Compound (16) could be isolated as the cis-Epoxy enenitrile (8). The structure of (8) was determined from a comparison of its spectral data with those of compound (1).…”

Photochemical Reactions. 153th communication. Photochemistry of acylsilanes: Photolyses and thermolyses of α,β‐epoxy silyl ketones

“…on a Brnker WP-80 CW (80 MHz) on W M 300 (300 MHz) instrument. For the description of the thermolysis procedures and the silylation of the thermolysis tubes, see [20].…”

Photochemical Rearrangements of 5,6‐Epimino‐5,6‐dihydro‐β‐ionone and Derivatives

“…Herein, it was of particular interest to compare the results with those obtained from photolysis of 1 and 2, especially as the thermal behaviour of (E)-3, (E)-4, and (E)-5 [5] is the same as that of the 0-and C-analogues [3] [6].…”