Olefins from thermal decomposition of N-sulfoximino-2-oxazolidones. A novel synthesis of bicyclo[3.3.1]non-1-ene

Abstract

3-Amino-2-oxazolidones (7a-g) were prepared stereospecifically by condensation of 2-hydroxyalkylhydrazines (obtained by hydrazinolysis of the corresponding epoxides) with diethyl carbonate in the presence of sodium methoxide or by Namination of a 2-oxazolidone (7a,e,h-j). The appropriate oxazolidone was prepared either by condensation of a 2-hydroxyalkylamine, obtained by ammonolysis of an epoxide, with phosgene (10a) or A.A'-carbonyldiimidazole (10b), or by nitrosation of a /3-hydroxycarbohydrazide (13). Oxidation of 3-amino-2-oxazolidones with lead tetraacetate in Me2SO gave the 3-sulfoximino derivatives 14a-j. Except for 14h, these sulfoximines underwent smooth pyrolysis at <140 °C to yield MeaSO, CO2, N2, and an olefin. The latter was shown to be formed via a syn elimination from the sulfoximine 14, probably involving the diazene 4 as an intermediate. Application of this olefin synthesis to a preparation of bicyclo[3.3.1]non-l-ene led from keto ester 16 to exo sulfoximine 24 which, by a syn elimination, gave Z isomer 15a in an isolated 53% yield. Synthesis of endo sulfoximine 28, followed by pyrolysis (150 °C), afforded carboxylic acid 28. The latter is believed to be formed via the highly strained £-bicy-

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Synthesis of sp3-rich chemical libraries based upon 1,2-diazetidines

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