Pyridine-4-carboxaldehyde oxime

Dihydro-2,3-quinoxalinedione, D-60279 Furo[2,3-6]pyridine-2-carboxaldehyde Oxime,... 

Thiazine-5-carboxaldehyde (254) has been converted to esters 255 by the action of AcOH and NaCN, followed by MnC>2 (Scheme 103) (85MI1). Thiazine-5-carbonitrile (256) has also been obtained from compound 254. This is first converted to the oxime, which is then dehydrated by acetic anhydride. Alternatively, 254 can be treated with CF3CONO2CCF3 in benzene and pyridine (Scheme 104), to also give 256. 

The enantioselective intramolecular formal 2+4-cycloaddition of acrylates and a, -unsaturated imines (99) catalysed by chiral phosphines (100), derived from amino acids, produced A-heterocycles (101) (Scheme 31). Chiral dirhodium(II) carboxamidates (102) catalysed the hetero-Diels-Alder reactions between 2-aza-3-silyloxy-l,3-butadienes and aldehydes to yield all cw-substituted l,3-oxazinan-4-ones in high yields and high enantioselectivity (98% ee)P The nickel-catalysed 4 + 2-cycloaddition of a, -unsaturated oximes with alkynes yielded 2,3,4,6-tetrasubstituted pyridine derivatives. The reaction of isoquinoline, an activated alkyne, and 4-oxo-4//-l-benzopyran-3-carboxaldehyde (103), in ionic solvents, produced 9a//,15//-benzo[a][l]benzopyrano[2,3-/t]quinolizine derivatives (105) via the zwitterion (104) selectively and in good yields (Scheme 32).The Diels-Alder cycloaddition of ethyl 3-(tetrazol-5-yl)-l,2-diaza-l,3-butadiene-l-carboxylates with -rich heterocycles, nucleophilic olefins, and cumulenes formed 3-tetrazolyl-l,4,5,6-tetrahydropyridazines regioselectively. The silver-catalysed formal inverse-electron-demand Diels-Alder... 

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