The base-catalyzed reaction of 4-nitro-3-oxobutyrate (6) with acetylacetone (8, Scheme 3), formylacetone (13, Scheme 4), formylcyclohexanone (31, Scheme 5), 2,4-dioxopentanoates 39 and 40 (Scheme 6), and 2,4,6-heptanetrione (2, Scheme 7) affords substituted 3-nitrosalicylates, products of a double aldol condensation. With unsymmetrical dicarbonyl compounds both regioisomers are formed. High selectivity was found in the case of P-keto-aldehydes 13 and 31 with preferred addition of the NO,-substituted carbon to the aldehyde carbonyl. The major products of these cyclocondensations, which are isolated in yields ranging from 20% to SO%, are all new compounds. Less successful are the conversions with b-alkoxy-and P-chloro-vinyl ketones (23, 25, and 26), and with alkinone 24, where the condensation products are formed in very low yield (Scheme 4 ) .Dicyclohexyl-18-crown-6 (0.25 equiv.). d, See [I]. ') 1,8-Diazabicyclo[5.4.0]undec-7-ene.
' )Without molecular sieves.