From 4. A mixture of NaOH (1.65 g, 41.3 mmol) and the ester 4 (10.0 g, 38.5 mmol) in 500 ml of water was heated at about 70 °C for 5 h, during which time most of the solid dissolved. The reaction mixture was cooled and filtered, and the filtrate was acidified with concentrated HC1. The resulting mixture was heated to boiling and then filtered while hot. and the collected solid was washed with water and dried in a vacuum oven to yield 4-oxo-4H-[l,3]thiazino[3,2a]benzimidazole-2-carboxylic acid; 8.86 g (93%); mp 230-232 °C dec; IR 5.84 µ , NMR (Me»SO-d«) 8.3 (m, 1), 7,8-7.3 (m, 3), 7.27 (s, li.

Aus dem Isoxazolidinen (I) erhält man mit Persäuren über diskutierte Zwischenstufen die Einschiebungsprodukte (II).

Nitrones for intramolecular 1,3‐dipolar cycloadditions: hexahydro‐1,3,3,6‐tetramethyl‐2,1‐benzisoxazoline reactant: 25.0 g. (0.16 mole) of 3,7‐dimethyl‐6‐octenal reactant: 23.4 g. (0.280 mole) of N ‐methylhydroxylamine hydrochloride product: hexahydro‐1,3,3,6‐tetramethyl‐2,1‐benzisoxazoline