Keywords: aroylketenes, (R)-, (S)-spiro-1,3-dioxin-4-ones, terpenoids, (4+2) cycloaddition.Substituted furan-2,3-diones react with aldehydes and ketones with the formation of substituted 6-aryl-1,3-dioxin-4-ones [1,2], displaying biological activity [3]. Continuing these studies we have investigated the effect of substituents in furandiones on the course of the reaction with optically active l-menthone, camphor, and allobetulone.As a result of the interaction of 5-arylfuran-2,3-diones 1a,b with menthone we obtained a mixture of approximately equal quantities of the stereoisomeric adducts spiro[(6-aryl-3,4-dihydro-2H-1,3-dioxin)-2,2'-(1-isopropyl-4-methylcyclohexan)]-4-ones 3a,b and 4a,b. According to data of 1 H NMR spectroscopy, compounds 3 and 4 exist as a mixture of diastereoisomers with (R)-and (S)-configurations of the spiro carbon atom. O O O R O O R O O O O R O O O R 1a,b 2a,b 3a,b 4a,b -CO  1-4 a R = H, b R = Me

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Methods for the production of 2-substituted thiazoline-4,5-diones and their thermolysis in the presence of nucleophiles and dienophiles are examined.

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