ABSTRACT
The first domino '2 : 1 condensation/intramolecular aldol' reactions of 1,3-bis(trimethylsilyloxy)-1,3-butadiene with tetraalkoxymethanes provide a convenient approach to 3-hydroxy-5-alkoxyhomophthalates. These products, which contain one free and one protected hydroxyl group, can be functionalized by palladium(0)-catalyzed cross-coupling reactions.
Subject(s)
Aldehydes/chemistry , Butadienes/chemistry , Methane/chemistry , Palladium/chemistry , Stereoisomerism , CatalysisABSTRACT
The TiCl(4)-mediated formal [3 + 3] cyclocondensation of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one afforded a variety of functionalized 4-methoxy-6-(trifluoromethyl)salicylates and 3-methoxy-5-(trifluoromethyl)phenols with very good regioselectivity. The Me(3)SiOTf-mediated cyclization of 1,3-bis(trimethylsilyloxy)-1,3-butadienes, containing no substituent located at carbon atom C-4 of the diene (R(1) = H), resulted in the formation of trifluoromethyl-substituted pyran-4-ones. In contrast, trifluoromethylated cyclohexenones were formed when dienes were employed which do contain a substituent located at carbon C-4 (R(1) not equal H).
Subject(s)
Fluorine/chemistry , Hydrocarbons, Fluorinated/chemistry , Methane/chemistry , Pyrans/chemistry , Chemistry, Pharmaceutical , Cyclization , Ligands , Molecular StructureABSTRACT
1-Hydroxy-3,5-dimethyl-2,4-benzodioates (4-hydroxyisophthalates) were prepared by [3+3] cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 3-ethoxycarbonyl-4-trimethylsilyloxy-3-penten-2-one which is synthesized from (symmetrical) ethyl 2-acetylacetoacetate. The [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with 3-alkoxy-2-alkoxycarbonyl-2-en-1-ones, readily available by reaction of beta-ketoesters with trialkyl orthoformiates, provide a convenient and regioselective approach to a great variety of 3-substituted 1-hydroxy-2,4-benzodioates that are not readily available by other methods.
Subject(s)
Alcohols/chemistry , Butadienes/chemistry , Catalysis , Bridged Bicyclo Compounds/chemistry , Cyclization , Hydrogenation , Silanes/chemistry , StereoisomerismABSTRACT
The formal [3+3] cyclization of 1,3-bis(silyloxy)-1,3-butadienes with readily available 2-arylsulfonyl-3-ethoxy-2-en-1-ones resulted in regioselective formation of 4-(arylsulfonyl)phenols.