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alpha-Ester-substituted 1,3-dienylphosphonates 7 and 8, prepared by the Knoevenagel condensation, underwent intramolecular [2 + 2] cycloaddition in the presence of Lewis acid to form bicyclo[4.2.0] (26-57% yield) and bicyclo[3.2.0]skeleton (14-38% yield), respectively. Similar treatment of homologous 1,3-dienylphosphonate 11 and 1,3,5-trienylphosphonate 12 resulted in the formation of ionone derivatives (30-94% yield). The intramolecular cycloaddition reaction was applicable to several conjugated dienes bearing an ester group.

N-Allyldiazoacetamides containing a phosphinyl group at the α-position underwent the intramolecular 1,3-cycloaddition, followed by 1,3-hydrogen shift to afford 6a-diethoxyphosphinyl-3a,4,5,6a-tetrahydropyrrolo[3,4-c]pyrazol-6(1H)-ones in 74—78% yields, while the corresponding α-phenylthio amide produced 1-phenylthio-3-azabicyclo[3.1.0]hexan-2-one in 74% yield via extrusion of N2 from the intramolecular 1,3-cycloadduct. In the application of these compounds to the conversion of functionality, the former gave a fused tricyclic heterocycle and the latter gave deallylated compounds.

The reaction of several substituted benzyl alcohols with 1 equiv of benzyltrimethylammonium tribromide (BTMA Br3) in carbon tetrachloride under basic or neutral conditions gave the corresponding benzaldehydes, and with 2 equiv of BTMA Br3 in aqueous alkaline solution and subsequent acid hydrolysis gave the corresponding benzoic acids, respectively, in satisfactory yields.

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