2-(2-Methyl-4-nitrophenylimino)-3-isobutyl-4-methylene-1,3-thiazolidin-5-one → 2-(2-Methyl-4-nitrophenylimino)-3-isobutylspiro[1,3-thiazolidine-4,2'-bicyclo[2.2.1]heptane]

Beteiligte Stoffe

Reaktionsschritte

(R)-N-Isobutylserine methyl ester HCl salt (Method B3a; 2.28 g, 10.8 mmol) was treated with SOCl2 followed by 2-methyl-4-nitrophenyl isothiocyanate in a manner analogous to Method C2a. The resulting material was purified by column chromatography (SiO2, gradient from hexane to 10% EtOAc/hex) to give 3-isobutyl-4-methylene-2-(2-methyl-4-nitrophenylimino)-1,3-thiazolidin-5-one (0.028 g, 10%) followed by (S)-3-isobutyl-4-carbomethoxy-2-(2-methyl-4-nitrophenylimino)-1,3-thiazolidine HCl salt (0.192 g, 56%). 3-Isobutyl-4-methylene-2-(2-methyl-4-nitrophenylimino)-1,3-thiazolidin-5-one: TLC (25% EtOAc/hex) Rf 0.40. (S)-3-isobutyl-4-carbomethoxy-2-(2-methyl-4-nitrophenylimino)-1,3-thiazolidine HCl salt: TLC (free base, 25% EtOAc/hex) Rf0.50.

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