Spiro[4H‐chromene‐4,5′‐isoxazolines] and Related Compounds: Synthesis and Reactivities.

Abstract

2006 Benzopyran derivatives R 0350 Spiro[4H-chromene-4,5'-isoxazolines] and Related Compounds: Synthesis and Reactivities. -The reaction of chromones (I) with methyl ketoximes (II) affords spiro compounds (IV), which are used for the preparation of derivatives (IX) and (X). Reactions of chromone (Ia) with hydrazones and acetophenone anil are also studied [cf. compounds (XII), (XIV), and (XVI)]. -(SOSNOVSKIKH*, V. Y.; SIZOV, A. Y.; USACHEV, B. I.; KODESS, M. I.; ANUFRIEV, V. A.; Russ. Chem. Bull. 55 (2006) 3, 535-542; Gorky Ural State Univ., Ekaterinburg 620083, Russia; Eng.) -R. Staver 52-144

Synthesis of Chromone-Related Pyrazole Compounds

“…Hydrazones of methyl ketones react with chromones at the carbonyl carbon (1,2-addition) to give, upon acidification, spiro(4 H -chromene-4,5′-pyrazolines). This type of compounds was obtained from the reaction of 2-trifluoromethylchromone 66 with ethyl 2-(1-phenylethylidene)hydrazine-1-carboxylate 67 which afforded spiropyrazoline 68 in 26% yield ( Scheme 19 ) [ 50 ].…”