Reductive alkylation of pyridinium salts. Part 2. Utilisation of di-, tetra- and hexa-hydropyridine esters

Design and syntheses of methyl 2‐methyl‐2‐[2‐(4‐benzoyl‐5‐phenyl‐7‐halo‐2‐azabicyclo[4.1.0]hept‐3‐ene)]acetates: novel inhibitors of cyclooxygenase‐2 (COX‐2) with analgesic‐antiinflammatory activity

“…The concerted addition of :CX 2 should therefore occur from the sterically less hindered lower face of the boat-shaped 1,4-dihydropyridine ring present in 9a-solid where the orientation of the C-4 phenyl substituent remains unchanged. These stereochemical and regiochemical assignments are consistent with the X-ray structure for 2-benzoyl-5-benzyl-7,7dibromo-4-ethoxycarbonyl-2-azabicyclo[4.1.0]hept-3-ene, prepared by reaction of 1-benzoyl-4-benzyl-3ethoxycarbonyl-1,4-dihydropyridine with :CBr 2 , in which the C=O moiety of the C-4 CO 2 Et substituent is antiperiplanar to the C3-C4 olefinic bond [McCullough et al, 1996].…”

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

“…137 N-Benzoyldihydropyridine derivatives form stable adducts, also usually in high yields (eq 24). 138 Many earlier examples of reactions of nitrogen heterocycles with dichlorocarbene, which frequently produced gem-dichlorocyclopropanes, are collected in ref 4.…”

Electrocyclic Ring-Opening Reactions of gem-Dibromocyclopropanes in the Synthesis of Natural Products and Related Compounds

“…Indeed attempted ring expansion of the azabicycloheptanes 111 and 112 with either silver nitrate or silver trifluoroacetate in various solvents failed, and use of collidine caused 112 to decompose. 125 In contrast, the cyclopropisoquinoline 113 (and its C-1 epimer) undergoes opening of the external bond adjacent to the heteroatom from use of methoxide ion in methanol; C-3 epimeric ethers are the primary products (Scheme 57). 126…”