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Stereoselective 1,3‐Dipolar Cycloadditions to ( S )‐1‐Benzoyl‐3‐(cyanomethylidene)‐5‐(methoxycarbonyl)pyrrolidin‐2‐one
Author(s) -
Škof Marko,
Svete Jurij,
Stanovnik Branko,
Golič Ljubo,
GoličGrdadolnik Simona,
Selič Lovro
Publication year - 1998
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19981216)81:12<2332::aid-hlca2332>3.0.co;2-q
Subject(s) - chemistry , diazomethane , isoxazole , stereoselectivity , nitrile , 1,3 dipolar cycloaddition , cycloaddition , medicinal chemistry , oxide , stereochemistry , organic chemistry , catalysis
(5 S )‐1‐Benzoyl‐3‐[( E )‐cyanomethylidene]‐5‐(methoxycarbonyl)pyrrolidin‐2‐one ( 5 ) was prepared in four steps from L ‐pyroglutamic acid ( 1 ). 1,3‐Dipolar cycloadditions of diazomethane ( 6 ) and 2,4,6‐trimethoxybenzonitrile oxide ( 7 ) gave substituted 1,2,7‐triazaspiro[4.4]non‐1‐en‐6‐one 12 and 1‐oxa‐2,7‐diazaspiro[4,4]non‐1‐en‐6‐one 13 in 38 and 20% de, respectively. On the other hand, reaction of 5 with N ‐phenylbenzonitrile imines 8 and 9 , generated in situ from the corresponding hydrazonoyl chlorides 10 and 11 , respectively, and Et 3 N, furnished racemic pyrrolo[3,4‐ c ]pyrazoles 14 and 15 in 61 and 56% de, respectively. Cycloaddition of nitrile oxide 7 , when performed in the presence of Et 3 N, led to pyrrolo[3,4‐ d ]isoxazole 16 in 85% de.