4- -1,2,3,6-tetrahydro- 4-hydroxy-1,2,3,4-tetrahydropyridine

Two polymorphic forms of 3- 2-[4-(6-fluorobenzisoxazol-3-yl)-l,2,3,6-tetrahydropyridin-l-yl]ethyl -2-methyl-6,7,8,9-tetrahydro-4//-pyrido[l,2-n] pyrimidin-4-one (137 R = H) were prepared (99MIP1). Racemic 9-hydroxy-2-methyl-3- 2-[4-(6-fluorobenzo[r/ isoxazol-3-yl)-l,2,3,6-tetrahydro-l-pyridyl] ethyl -6,7,8,9-tetrahydro-4//-pyrido[l, 2-n]pyrimidin-4-one was resolved into its (R)- and (5)-isomers (OOMIPIO). 

To a solution of the (+)-methyl 2-[2-(N-phenylsulfonyl)indolyl]-2-hydroxy-3-[3-(N-allyl-5-ethyl-l,2,3,6-tetrahydropyridine)]propionate (a mixture of diastereomers at C-2) in dry dimethoxyethane at -50°C under argon was added sodium naphthalenide (1 M in THF). The mixture was quenched with trifluoroacetic acid, and extracted with ethyl acetate (3 times 10 ml). The extract was washed with saturated aqueous NaHC03 solution, dried (MgS04) and evaporated in vacuo to give the (+)-methyl 2-(2-indolyl)-2-hydroxy-3-[3-(N-allyl-5-ethyl-l,2,3,6-tetrahydro-pyridine )]propionate. The mixture of diastereomers was not separated but chromotagraphed over silica gel eluting with hexane/ethyl acetate/10% aqueous NH4OH/MeOH (5 1 1) to remove more polar impurities. 

The oxidation of 1,4-dihydropyridines with dimethyldioxirane provides dimeric tetrahydropyridines fused as a 1,4-dioxane. These products can be converted to useful iminium ion precursors and 2-substituted-3-hydroxy-l,2,3,4-tetrahydropyridines <97CC213>. The cycloaddition of 1,4-dihydro- and 1,4,5,6-tetrahydro-nicotinates with cyanoalkenes gives a mixture of regioisomers. No isomerization of the cis/trans relationship is observed with Z- or -but-2-enenitrile indicating a consorted cycloaddition mechanism. Low diastereoselectivity in... 

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