Chloronitroso sugars, hetero Diels-Alder

The a-chloronitroso-sugar 58 was synthesized by reaction of the corresponding oximino-lactone with tert-butyl hypochlorite and used as a dienophile in asymmetric hetero-Diels-Alder reactions. Adducts were produced as hydrochloride salts in 93-99% ee with simultaneous solvolytic removal of the auxiliary. ... 

Further examples of hetero-Diels-Alder reactions of carbohydrate-derived chloronitroso compounds have been reported. When the chloronitroso compound 214, made from D-xylose, reacted with cycloheptadiene in the presence of some water, the cycloadduct 215, which could be used in a synthesis of (-)-physoperuvine, was obtained in a96% ee, together with the sugar ketone which can be recycled to 214. The pseudoenantiomeric species 216, from L-sorbose, gave the dihydrooxazine 217 on reaction with cyclohexadiene, again in high e.e. The chloronitroso compound 218, easily accessible from D-ribose, underwent... 

Hetero Diels-Alder reactions involving chloronitroso sugars have been described by Vasella (42). A single cycloadduct was obtained in the reaction of 67 with cyclohexadiene. Compound 67 was obtained from D-mannose. The carbohydrate moiety was cleaved from the cycloadduct by in situ methanolysis to give 68. 

The preparation of a conduramine derivative 90 by hetero-Diels-Alder reaction of a chloronitroso sugar derivatives with cyclohexadienes has been reported. (See Vol. 25, p. 210, ref. 73 for similar work). 

---