Proton magnetic resonance studies of sym-oxepin oxide

Abstract

syw-oxepin oxide (1) in aprotic solvents (CDCI3, CH2CI2, CD2CI2, THF, or CH3CN) with catalytic amounts of MeSOsH led within seconds to the generation of 13. In CDCI3 the addition of MeSC^H (0.1 mol %) catalyzes the quantitative ( NMR) rearrangement of 1 to 13: ir (CDC13) 1725, 1680, 1620, 1260 cm-'; NMR (CDC13, 100 MHz) 9.51 (1 H, d), 6.50 (2 H, m), 4.90 (2 H, m), 3.64 (1 H, m); uv (CH3CN) Xmax 246 (e 590), 310 (110); mass spectrum (70 eV) m/e parent 110, base 81. Exact mass of p-nitrophenylhydrazone: caled forC12Hi,N303, 245.0800; found, 245.0797. Reduction of 13 to 4-Hydroxymethyltetrahydropyran (15). The catalytic reduction of 13 to 4-hydroxymethyltetrahydropyran (15) was achieved in THF-EtOH over Raney nickel catalyst. The catalyst was prepared as for the reduction of 1 to 14, except that the metal was both washed and stored under EtOH rather than THF.

Dimethyldioxirane Converts Benzene Oxide/Oxepin into (Z,Z)-Muconaldehyde and sym-Oxepin Oxide: Modeling the Metabolism of Benzene and Its Photooxidative Degradation

“…Thus, demetalation of the copper(I) complex 4 was performed with 20% aqueous ammonia in the temperature range −20 to −30 °C, to liberate the azo diepoxide 5 . This underwent decomposition in CDCl 3 at room temperature, with extrusion of nitrogen, to give sym -oxepin oxide 3b (see Scheme ): 1 H NMR (200 MHz, CDCl 3 ) δ 6.34 (2H, d), 5.14 (2H, ddd), 3.33 (2H, dd) (see ref for analysis of this spin system). The solvent was removed (−42 °C at 0.02 mmHg) and the residual sym -oxepin oxide ( 3b ) was taken up in deuterated acetone: 1 H NMR (200 MHz, acetone- d 6 ) δ 6.54 (2H, d, J = 7.5 Hz, 2-H, 7-H), 5.33 (2H, ddd, J = 2.1, 3.5, 7.5 Hz, 3-H, 6-H), 3.43 (2H, dd, J = 2.1, 3.5 Hz, 4-H, 5-H).…”

Conformation and Cope rearrangement of sym-oxepin oxides

“…H NMR). Data for 15c: NMR (py-ds) (Me4Si) 1.68 (m, 10 H), 4.91 (d, J = 7 Hz, 2 H), 6.28 (d, J = 7 Hz, 2 H): IR (py-t/5) 1675, 1656 cm-1…”

“…Subsequently, we detailed3 our conversion of benzene oxide oxepin to sym-oxepin oxide (3, R = H, Scheme II), and studied the conformation and Cope rearrangement of 3 (R = H) by NMR spectroscopy. 4 Other studies revealed the Cope rearrangement of a methylated derivative5 and helped define the scope6 of our synthetic approach to oxepin oxides. Further, we reported the synthesis of the bridgehead diene 10a7 (Scheme IV) and characterized a derivative of 10a by X-ray crystal analysis.8…”

“…A priori one must consider two stereochemical outcomes for the Cope rearrangement of a chiral oxepin oxide (4, Scheme III). In principle, 4 could interconvert, via Cope rearrangement, with its diastereomer 5 (5 ^4) or with its rotamer 6 (6 = 4). The interconversion 4^5 would proceed via a transition state resembling cisoid conformation 3a (Scheme II); the degenerate rearrangement 4 === 6 would proceed via a transoid transition state9 (cf.…”