2,2 -bi-l,2,3,4-tetrahydropyrimidine

JOU2236). In the case of TCE 33 the cyclization proceeds without a catalyst on short heating (73CB914). However, continuous heating leads to bis(6-hydroxy-2,4-dioxo-l,2,3,4-tetrahydropyrimidin-5-yl)malononi-trile. Modern modification involves a three-component reaction of aromatic aldehyde, malononitrile, and barbituric acid with solvent-free conditions under microwave irradiation (4-8 min, 70-95%) (03TL8307). 

Ligand abbreviations (6-Mepy)(py)2tren and (6-Mepy)2(py)tren = tris[4-[(6-/ )-2-pyridyl]-3-aza-6-butenyl]amme, R = H or CH3 HB(pz)3 = hydro-tris(pyrazolyl)borate paptH = 2-(2-pyridylamino)-4-(2-pyridyl)thiazole phenmethoxa = 3-[2-(l,10-phenanthrolyl)]-5-methyl-l,2,4-oxadiazole pyimH = 2-(2 -pyridyl)itnidazole pybimH = 2-(2 -pyridyl)benzimidazole ppa = JV -(2-pyridylmethyl)picolineamidine tpmbn = tetrakis(2-pyridylmcthyl)-meso-2,3-butane-diamine tppn = tetrakis-(2-pyridylmethyl)-l-methyl-l,2-propanediainine tpchxn = tetrakis(2-pyridylmethyl)-tra s-l,2-cyclohexanediamine biz = 2,2 -bi-1,4,5,6-tetrahydropyrimidine. 

The ligand 3,4,5,6-tetrahydropyrimidine-2(l//)-thione (THPT) forms an S-bonded complex, BiCl3(THPT)3.225 The crystal structure (81) shows a fac octahedron. Interestingly, with bismuth perchlorate Bi(C104)3(THPT)5 is formed. 

---