220205-70-9Relevant academic research and scientific papers
Stereoselective 1,3-dipolar cycloadditions to (s)-1-benzoyl-3- (cyanomethylidene)-5-(methoxycarbonyl)pyrrolidin-2-one
Skof, Marko,Svete, Jurij,Stanovnik, Branko,Golic, Ljubo,Golic-Grdadolnik, Simona,Selic, Lovro
, p. 2332 - 2340 (2007/10/03)
(5S)-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 Et3N, 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 Et3N, led to pyrrolo[3,4-d]isoxazole 16 in 85% de.
