2- carbonyl perhydropyrido

Rhodium-catalyzed reaction of iV-butenyl-l,3-propanediamines 538 with a mixture of H2 and CO gave a mixture of hydroformylated 539, 540, and carbonylated products 541, 542 in the presence of a phosphine (PPI13, PBU3, P(C6Hn)3, PO-toDj) (Equation 91) <1997T 17449, 1997TL4315>. When the hindered biphosphite, BIPEPHOS, and a 9 1 or 1 1 mixture of H2 and CO were used, only perhydropyrido[l,2- ]pyrimidine 539 (R = H) was formed from 538 (R = H). 

Cross double carbonylation of 2-hydroxymethylpiperidine in the presence of PdCl2(MeCN)2-CuI as catalyst under CO and 02 at ambient temperature in an autoclave afforded perhydropyrido[2,l-c][l,4]oxazine-3,4-dione [87JAP(K)87/212377,87JCS(CC)125],... 

The carbonyl group in the side chain at position 8 of perhydropyrido[l,2-c][l,3]oxazines (33) and (34) was converted to the dimethyiacetal on the treatment with triethyl orthoformate in methanol in the presence of p-toluenesulfonic acid (96SL100). 

Cyclization of l-[iV-(un)substituted amino(thio)carbonyl]-2-[phenyl (methoxycarbonyl)methyl]piperidines in boiling ethanol containing hydrogen chloride gave 4-phenyl-2-(un)substituted perhydropyrido[l,2-c] pyrimidine-1,3-diones (64JMC146). 

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