Chemoselectivity and stereoselectivity in the condensation reactions of 4,4′-diethyl-2,2′-perhydrobipyrimidine

✍ Scribed by Roger W. Read; Xue-qin Shi

• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 801 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00961-2

✦ Synopsis

Rac 1,3-pentanediamine reacts with glyoxal to give a 1:1 mixture of diastereomers from which can be isolated (2R*,2'S*,4S*,4'R*)-4,4'-diethylperhydro-2,2'-bipyrimidine. Subsequent treatment with HCHO, MeCHO, EtCHO, and i-PrCHO gives cis and to a lesser extent trans fused 1:1 condensation products, which are 4a, 4b-cis-3,6-diethylperhydro-4,5,8a,9a-tetraazafluorene and 4a,4b-trans-l,6-diethylperhydro-4,5,8a,9a-tetraazafluorene derivatives, or tetracyclic cis fused 1:2 condensation products, 8b, 4a,7a,fluorenes, respectively, depending on conditions. 2-Phenylacetaldehyde reacts to give cis and trans 2-benzyl-4-ethylhexahydropyrimidine. The effects of aldehyde and solvent upon the outcome are discussed.