Saeko Matsugashita

Photochemistry of N-acylimino-isoquinolinium and -quinolinium betaines

Abstract The photochemical behavior of N-acyliminoisoquinolinium and -quinolinium betaines has been investigated. In contrast to pyridinium betaines, the principal course of reaction is the 1,2-migration of N-acylamino groups. Substituent effects as well as solvent effects are observed. The results are rationalized in terms of diaziridine intermediates.

Synthesis of the physostigmine ring system from cycloprop[b]indoles

The transformation of cycloprop[b]indoles into derivatives of the physostigimine ring system is described.

Photo-isomerisation of 1-acetyl-2-cyano-1,2-dihydroquinolines to N-acetylbenzoazetines

1-Acetyl-2-cyano-1,2-dihydroquinolines isomerise photochemically to give N-acetylbenzoazetines, the formation of which is rationalised in terms of benzoazahexatriene intermediates.

Photochemical synthesis of 2,3-homoindoles

Irradiation of ethyl 2-cyano-4-methyl-1,2-di-hydroquinoline-1-carboxylates in ethanol gives stereospecifically ethyi endo-1-cyano-6b-methyl-1, 1a,2,6b-tetra-hydrocycloprop[b]indole-2-carboxylates(2,3-homoindoles) in 59–61% yields, which are shown to be useful synthetic intermediates for indole derivatives.

Photochemical reactions of 1,2-dihydroquinolines

Irradiation of ethyl 2-substituted 1,2-dihydroquinoline-1-carboxylates gives rise to allenic compounds and ethanol adducts depending upon the solvent used; product formation is rationalised in terms of benzoazahexatriene intermediates.

Photochemistry of ethyl 4-substituted 2-cyano-1,2-dihydroquinoline-1-carboxylates (Reissert compounds): syntheses of cycloprop[b]indoles

Irradiation of ethyl 4-subslituted 2-cyano-1,2-dihydroquinoline-1-carboxylates (Reissert compounds) in ethanol gives ethyl 6b-substituted 1-cyano-1,1a.2,6b-tetrahydrocycloprop[b]indole-2-carboxylates. The stereochemistry of the products has been determined by n.m.r. spectroscopy.

Photochemistry of ethyl 2-cyano-1,2-dihydroquinoline-1-carboxylates (Reissert compounds): synthesis of 2-cyanomethylinodole-1-carboxylates

Irradiation of ethyl 2-cyano-1,2-dihydroquinoline-1-carboxylates (Reissert compounds) gives ethyl N-[o-(3-cyanoallenyl)phenyl]carbamats, which are readily converted into ethyl 2-cyanomethylindole-1-carboxylates by treatment with alumina.