3.4.7.8- Tetrahydro-lH,6H-pyrido

Ring opening of 3-oxo-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l-a]pyra-zine-9-carboxylate 181 occurred on the action of NaOMe to give tetrahy-dropyridinecarboxylate 182 (06T5697). 

The treatment of 6(S)-(iodomethyl)-4(R)-phenyl-l(R)-(trifluoromethyl)-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l-c][l,4]oxazin-l-ol with NaH and I2 under microwave irradiation in CHC13 gave 6(S)-(iodomethyl-4(R)-phe-nyl-9a-(trifluoromethyl)-9-iodoperhydropyrido[2,l-c][l,4]oxazin-l-one in 90% yield (080L605). 

Reaction of (R)-phenylglycinol with dimethyl acetylenedicarboxylate in boiling MeOH 12 h, followed by the treatment of the reaction mixture with acryloyl chloride yielded l,6-dioxo-3,4,7,8-tetrahydro-lH,6H-pyrido [2,l-c][l,4]oxazine-carboxylate 470 (07LOC4). 

Reactions of y-chloropropylamines HC1 471 and acetylene compound 472 in MeCN in the presence of a base, 4 A MS and BU4NI afforded 3-oxo-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l -c] [1,4]oxazine-9-carboxylates 473 (06T5697). Similar reactions of acetylene derivatives 474 provided 3-oxo-3,4,7,8-tetrahydro-lH,6H-pyrido[2,l-a]pyrazine-9-carboxylates 475. 

---