Vapor-phase thermolyses of 3-hydroxy-1,5-hexadienes. II. Effects of methyl substitution

Participation of acetylenic bonds in pericyclic reactions. Thermal cleavage of .beta.-hydroxyacetylenes

“…arrangement. 23 Similarly, the acetylenic oxy-Cope rearrangement of l-hexen-5-yn-3-ol14 and its 3-methyl derivative16-16 appears to be a process competing with /3-hydroxy acetylene cleavage. Although activation parameters for either competitive process could not be determined, both processes occurred at a faster rate than the corresponding reactions of their olefinic analogs in l,5-hexadien-3-ol.…”

“…For preparative scale thermolysis studies, the system previously described was utilized. 23 The products isolated were identified as follows.…”

The suitability of anion-accelerated oxy-Cope rearrangement as a probe to study π-facial selectivity. An experimental study with (6-methyl-1-oxa-4-thiaspiro[4.5]dec-6-en-7-yl)(allyl)methanols †

“…Even with the use of potassium and sodium salts of alkoxides in appropriate solvents Evans et al 25 observed little dissociation-recombination of the type that Viola et al 22 have reported, despite the fact that metal alkoxides of homoallylic alcohols have been documented to undergo cleavage to ketones and allylic organometallics. 26 Exceptions to this were, however, found in those cases where a quaternary center was generated as a consequence of the Cope process and enones were isolated as the predominant products.…”

“…Viola et al 22 have studied the high temperature (340-390 ЊC) vapor phase thermolysis of a series of methyl substituted 3hydroxyhexa-1,5-dienes and noted the formation of some cleavage products along with the products from a normal Cope rearrangement. This was interpreted on the basis of two competing concerted bond reorganizations, both of which proceeded through cyclic six-membered ring transition states as shown in Scheme 6.…”

The Most Well-Known Rearrangements in Organic Chemistry at Hand

“…The Oxy-Cope rearrangement involves compounds with a hydroxyl group affixed to C-3 so that the rearranged product is an enol which tautomerizes to the keto form as outlined in equation ( 44) [100]. The speed of this peculiar rearrangement can be enhanced by converting the alcohol to an alkylate and the reaction is therefore called anionic Oxy-Cope rearrangement.…”