Nitroimidazoles: Part XX. Reactions of 2,4-dinitroimidazole with 2-haloethanols, 3-chloropropionitrile & propylene oxide

Abstract

The reaction of 2,4-dinitroimidazole (1) with 2-chloroethanol, 3-chloropropanoI or 3-chloropropionitrile gives 2-chloro-4- nitroimidazole (7) and not 4-chloro-5-nitroimidazole (3) as claimed in earlier literature. 1 and 2-bromoethanoI likewise yield 2- bromo-4-nitroimidazole(ll). 7 is methylated to isomeric methyl derivatives 8 and 13 and 11 to 12 and 14. In the reaction of 1 with 3-chloropropionitrile, other products 9, 10 and 16 have been isolated. 1 is unaffected by 2-chloropentane. 2-Chloroethanol and 1-methyl-2,4-dinitroimidazole (2) afford 8. HCI formed from hot 2-chloroethanol in the presence of nitroimidazoles seems to be responsible for the displacement of N0₂ group at position-2 with chlorine. 1 and propylene oxide yield imidazooxazoline (18) and the dinitro alcohol (19) along with a small amount of the isomer 20. 19 is transformed to imidazooxazoline (21) by excess propylene oxide or piperidine. 7 and propylene oxide afford isomeric alcohols 26 and 27, the latter being readily transformed to 18. Piperidine opens the oxazoline ring in 18 to yield 25. ¹H and ¹³CNMR data are used to derive new structures.