Epoxycarbinyl solvolyses. Lack of significant participation by epoxide oxygen in the hydrolysis of acyclic secondary epoxycarbinyl substrates

Abstract

Aus dem trans‐ Carbinol (I) werden die isomeren Epoxide (IIa) und (IIIa) erhalten und in die Brosylate (IIb) bzw. (IIIb) übergeführt.

Epoxycarbinyl solvolyses. The solvolytic reactions of syn- and/anti-9-oxabicyclo[6.1.0]non-2-yl p-bromobenzenesulfonates

“…Yields correspond to relative areas of product peaks on a GLC tracing. 6 Analyzed by gas chromatography on a 6 ft X lA in., 5% diethylene glycol succinate column. The temperature of the chromatograph oven was programmed from 60 to 160 °C at 3 °C min.…”

“…10-18 eu higher than the entropies of activation for solvolysis of the three and erythro isomers of 3,4-epoxy-2-pentyl brosylate in the same solvent. 6 The latter acyclic brosylates undergo predominant inversion at the ionizing center when hydrolyzed in an acetone-water solution and therefore their more negative entropies of activation may reflect the Sn2 character of the transition states. Consequently, the more positive entropies of activation for solvolysis of 2b and 3b may reflect the absence of strong solvation at the backsides of the ionizing centers.…”

“…The major product 43 was separated from the rest by preparative chromatography on a 6 ft X % in., 10% SE-30 column: isolated yield 0.20 g (ca. 25%); UV (cyclohexane) 215 nm (e 294); IR (CCI4) 1650 (C=C) cm'1; IR (CS2) 760, 767 (CH=CH) cm-1; NMR (CC14) 1.6 Im, 8 ), 2.1 (m, 2 H, allvlic), 3.34 (s, 3 H, OCH3), 4.48 (t, J = 5 Hz, 1 H, CHOCH3), 4.85 (q, J = 6 Hz, 1 H, CH=CHCH2), 6.04 (d, J = 6 Hz, 1 H, OCH=CH); molecular weight (mass spectrum) 156.…”

A Facile C−C Bond Cleavage in the Epoxides and Its Use for the Synthesis of Oxygenated Heterocycles by a Ring Expansion Strategy

“…It has also been reported that the oxiranyl carbinyl radicals can lead to products from C−C bond cleavage, and in a few cases ring-expanded heterocycles have been synthesized . Elegant mechanistic studies have been reported for the oxiranyl carbinyl cations, both from the theoretical and experimental points of view . These intermediates, which are usually generated under solvolytic conditions, follow different reaction pathways to give a complex mixture of products via C−O or C−C bondcleavage 6d.…”

“…Elegant mechanistic studies have been reported for the oxiranyl carbinyl cations, both from the theoretical and experimental points of view . These intermediates, which are usually generated under solvolytic conditions, follow different reaction pathways to give a complex mixture of products via C−O or C−C bondcleavage 6d. However, to the best of our knowledge, only one example of oxocene 7 and two examples of the bicyclic oxepenes 6g have been synthesized via ring expansion of the corresponding oxiranyl cations.…”