David C. Lankin

The sensitized photooxygenation of methyl substituted 1,2-diphenylcyclobutenes

Abstract A series of Me substituted 1,2-diphenylcyclobutenes was subjected to dye-sensitized photooxidanon in the presence ofmethylene blue. In the case of the 3,3-dimcthyl-, 3,3,4-tnmethyl- and 3,3,4,4tetramcthyl, 2-diphcnylcyclobutencs, the sensitized oxidations arc accompanied by ring-contraction with concomitant ortho hydroxylation of one aromatic nucleus. When electron transfer induced photooxidation techniques utilizing 9,10-dicyanoanthraccne (DCA) as a sensitizer are employed with the series of Me substituted diphcnykyclobutenes, the reactions take a markedly different course and a broad spectrum of oxidation products are obtained including, most notably, ozonides of the cyclobutencs. The mechanisms of these conversions are addressed and the significance of the results discussed.

Oxopyrazoline-spiro-oxirans. A new class of reactive heterocycles

Chemical and spectral properties of a series of 1-oxa-5,6-diazaspiro[2.4]hept-6-en-4-ones, synthesized by the oxidation of 4-alkylidene- or 4-arylidene-1-aryl-2-pyrazolin-5-ones are reported.

Photoinduced cycloadditions of electron deficient nitrones to alkenes

Abstract Oxaziridines are proposed as intermediates in the photoinduced cycloadditions of electron deficient nitrones to dipolarophiles.

Structural studies on a novel reaction product of malononitrile with aβb,δ-unsaturated allene aldehyde

Abstract Condensation of 2,5,5-trimethylhexa-2,3-dien-6-a1 with malononitrile affords an unexpected product, C15H16N4X, ( 3 ), the structure of which was partially characterized by spectral (infrared, ultraviolet, 1H, and 13C nmr) methods and fully elucidated by single crystal X-ray analysis. 3 is l-cyano-2-amino-3-(2-propenyl)-5,5-dimethy-6- dicyanomethycycohexa-l,3-diene in a half-chair conformation. Conjugation of the cis -aminocyanoethenyl moiety leads to intermolecular hydrogen bonding in the crystal. A reaction sequence and its mechanistic implications are proposed.