Heterocyclische β-Enaminoester, 53. Neue 5,8-Dihydropyrido- und 4H-Pyrano[2,3-d]pyrimidine

✍ Scribed by Wamhoff, Heinrich ;Paasch, Joachim

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 489 KB
• Volume: 1990
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1990199001180

✦ Synopsis

Heterocyclic β‐Enamino Esters, 53. — Novel 5,8‐Dihydropyrido‐ and 5__H__‐Pyrano[2,3‐d]pyrimidines

The 1,4‐dihydropyridine enamino esters 1a and 4 react with phenyl isocyanate to afford the ureas 2 and 5, resp., which are cyclized to yield the 5,8‐dihydropyrido[2,3‐d]pyrimidines 3 and 6, resp., while the 1,4‐dihydropyridine bisenamino ester 7a gives accordingly, via bisurea 8, the pyrido[2,3‐d:6,5‐d′]dipyrimidine 10. The 2‐amino‐4__H__‐pyran‐3‐carboxylate 11 is smoothly phosphorylated to form 12. Treatment of 12 with phenyl isocyanate results in a ring closure to the 4__H__‐pyrano[2,3‐d]pyrimidine 14. Similarly and according to this principle, the 5,8‐dihydropyrido[2,3‐d]pyrimidine 16 is smoothly formed upon treatment of the iminophosphorane 15 with phenyl isocyanate, while the 2,6‐diamino‐1,4‐dihydropyridine 7b after phosphorylation affords the mono‐iminophosphorane 17, which undergoes cyclization with isocyanate to the 5,8‐dihydropyrido[2,3‐d]pyrimidine 18. With isopropylsulfamoyl chloride 1b and 7a form the mono‐ and bissulfamides 20 and 21, resp., which could not be cyclized further.