3.4- Dihydro-27/-pyrido oxazinium

Reaction of 9-benzyloxy-3,4-dihydro-277-pyrido[2,l- ][l,3]oxazinium mesylate with C5H9NH2 and BnNH2 occurred at position 9a, while with sterically hindered amines (e.g., Bu NH2, secondary amines), PhNH2 and NaN3 reacted at position 2 to give l-(3-hydroxypropyl)-2-(substituted imino)-3-benzyloxy-l,2-dihydropyridines and... 

The equilibrium mixtures of 3-hydroxy-3-methyl-3,4-dihydro-lH-pyrido [2,l-c][l,4]oxazinium chloride 159a, its 4,4-dideutero derivatives 161a (06PJC1039) and those of 3-hydroxy-3-phenyl-3,4-dihydro-lH-pyrido [2,l-c][l,4]oxazinium bromide 159b and 161b (06JST36) with their ring-opened forms 160 and 162 were characterized by FTIR, 1H, 13C, and 15N NMR spectra in DMSO and D20. 

The mercapto group of 3-mercapto-3,4-dihydro-l//-pyrido[2,l-c][l,4]-oxazinium salt reacted with p-nitrobenzyl (55,65)-2-(diphenylposphono) oxy-6-[l(/ )-hydroxyethyl]carbapen-2-em-3-carboxylates in the presence of N,jV-diisopropylethylamine (86EUP168707, 86EUP169410). 3,4-Dihydro-l//,8//-pyrido[2,l-c][l,4]oxazine-8-thione was alkylated with diphenyl-methyl 3-iodomethyl-7-acylamino-3-cephem-4-carboxylates [89JAP(K) 89/290683],... 

Depending on the reaction conditions, treatment of 4-hydroxymethyl-3,4-dihydro-l-oxo-l//-pyrido[2,l-c][l,3]oxazinium chloride with NH3 afforded either 4-hydroxymethyl-l,3-dihydropyrido[2,l-c][l,3]oxazin-l-one or different ring-opened products (92JOC5764). 

Treatment of 2-(2-vinyloxyethyl)pyridine with Bra in CCI4 at 0°C gave Tbromomethyl-2,3-dihydro-l//-pyrido[l,2-c][l,3]oxazinium bromide (86KGS1396). 

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