Tetrahydro-1,3-oxazin-2-ones, reduction

Reduction of 3-substituted-3,4,7,8-tetrahydro-l//,6//-pyrido[l,2-t][l,3 oxazin-l-ones with NaBHjCN in boiling MeOH, and with NaBH4 in AcOH, afforded 4a-epimeric mixtures of perhydro derivatives <2005T1595>. 

Lithium aluminum hydride reduction of tetrahydro-l,3-oxazin-2-ones 434 results in the corresponding A -methyl-substituted 1,3-amino alcohols 435 (60JA4656 87TL1623). 

Lithium aluminum hydride reduction of the tetrahydro-l,3-oxazin-4-ones 436 (cis, n = 1, 2 trans, n = 2 R, = H, alkyl, aryl) can easily be... 

Bromopropylamine was reported to form tetrahydro-l,3-oxazin-2-one in moderate yield when treated with the carboxylating reagent (O2 /C02) formed by the electrochemical reduction of oxygen in acetonitrile in the presence of carbon dioxide <1997JOC6754>. 

The tetrahydro-l,4-oxazin-2-ones are lactones and have been reduced to the corresponding hemiacetals (tetrahy-dro-l,4-oxazin-2-ols) using diisobutylaluminium hydride <1998T10419> and lithium triisobutylborohydride <2004TL8917>. Rather remarkably, treatment of the tricyclic tetrahydro-l,4-oxazin-2-one 210 with LAH and boron trifluoride results in complete reduction of both carbonyl groups to afford the tetrahydro-l,4-oxazine 211 (Equation 15) <1978CB1164>. 

The usual route to tetrahydro-l,3-oxazines is via the reduction of dihydro forms however, direct syntheses are not difficult to achieve. One obvious approach is the combination of aldehydes and ketones with 3-aminopropanols, and another, which has proved most useful... 

Reduction of a spiro compound, dodecahydro-3,3 -bi-l//,3//-pyrido[l,2-c][l,3]oxazine, with sodium amalgam in acetic acid led to reductive cleavage of one of the two tetrahydro[l,3]oxazine rings [71LA(753)27]... 

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