A Convenient Procedure for the Synthesis of Substituted 3‐α‐Haloalkyl‐5,6‐dihydro‐4H‐1,2‐oxazines.

Abstract

A Convenient Procedure for the Synthesis of Substituted 3-α-Haloalkyl-5,6-dihydro-4H-1,2-oxazines. -The title compounds are directly obtained from cyclic nitronates and trimethylsilyl halides. The latter [cf. (VI)] can be readily subjected to nucleophilic substitution reactions with cyanide or malonate. Interestingly, under milder reaction conditions the intermediate enamines (IV) and (VII) can be isolated in excellent yields. -(KLENOV, M. S.; LESIV*, A. V.; KHOMUTOVA, Y. A.; NESTEROV,

Construction of Saturated Oxazolo[3,2-b][1,2]oxazines via Tandem [3+2]-Cycloaddition/[1,3]-Rearrangement of Cyclic Nitronates and Ketenes

“…23 rel-(4S,6S)-3-Ethyl-6-methoxy-4-(4-methoxyphenyl)-6-methyl-5,6-dihydro-4H-1,2-oxazine 2-Oxide (2h). 25 Prepared from (E)-1methoxy-4-(2-nitrobut-1-en-1-yl)benzene 1e 26 (1.04 g, 5 mmol) and 2-methoxypropene (0.95 mL, 10 mmol) with SnCl 4 (0.7 mL, 6 mmol) in 25 mL of CH 2 Cl 2 . Reaction was conducted at −94 °C for 20 min, followed by an aqueous workup.…”

“…NMR spectra are in agreement with published data. 25 rac-4-(4-Methoxyphenyl)-3,6,6-trimethyl-5,6-dihydro-4H-1,2-oxazine 2-Oxide (2i). 27 Prepared from (E)-1-methoxy-4-(2-nitroprop-1en-1-yl)benzene 1f 24 (50 g, 259 mmol) and 2-methylpropene (29 g, 518 mmol) with SnCl 4 (30.3 mL, 259 mmol) in 450 mL of CH 2 Cl 2 .…”