palladium(0)-catalyzed, Cu(I)-mediated synthetic route to trisubstituted olefins and conjugate dienes has been developed via oxo directing Liebeskind–Srogl cross-coupling reactions of gem-dihaloolefin-type α-oxo ketene dithioacetals with aryl and alkenylboronic acids. The synthetic protocol has demonstrated rare examples of transition-metal-promoted transformations of ketene dithioacetals, providing a novel route to
Δ3-Dihydropyrans and tetrahydropyrans by reduction of pyrylium salts with sodium borohydride in acetic acid
作者:Teodor-Silviu Balaban、Alexandru T Balaban
DOI:10.1016/s0040-4039(00)95365-6
日期:1987.1
major reduction products with triacetoxyborohydride (NaBH4 in AcOH) of 2,4,6-trisubstituted pyrylium salts bearing alkyl substituents in the 2- and/or 6- position are the Δ3-dihydropyrans with 2- and 6- substituents and the all--2,4,6-trisubstituted tetrahydropyrans. Δ3-Dihydropyrans are shown to be formed 2H-pyrans by a 1,4 reduction while tetrahydropyrans result from 4H-pyrans by reduction of both
Synthesis of functionalised furans and pyrroles through annulation reactions of 4-pentynones
作者:Antonio Arcadi、Elisabetta Rossi
DOI:10.1016/s0040-4020(98)00953-3
日期:1998.12
A new approach to 4-pentynones through palladium-catalysed coupling reaction of the ready available 2-propynyl ketones with aryl iodides and/or vinyl triflates is proposed. Annulation reactions of both 2-propynyl ketones and 4-pentynones gave functionalised furans using potassium tert-butoxide in DMF and functionalised pyrroles in the presence of benzylamine or ammonia, respectively in good to high
Different substituted furans are syntetised by cyclization of 4-pentynones using potassium tert-butoxide in DMF. A different reaction pattern is observed when the same compounds were treated with sodium methoxide in MeOH. A new approach to 2-propargyl-carbonyl compounds is also proposed.