Carbamate 0- sodium cyanide

Etherification of isohexides with substituted-benzyl chloride in aqueous sodium hydroxide, or by means of sodium hydride in dimethyl sulfoxide, yields mixtures of mono- and bis-ethers, which can be conventionally separated by distillation or by column chromatography.176 The preparation of some phenyl ethers was also described, using the tosylate-phenoxide exchange reaction. Monoethers (88) synthesized in this way were transformed into carbamates (89) by reaction with sodium cyanide-trifluoroacetic acid (see Scheme 18). 

Note Sodium diethyl dithio carbamate crystals or 2% sodium cyanide solution, (used generally to... 

In the synthesis of (—)-lupinine (926) by Santos et al., (lR,2S,5R)-8-phenyhnenthol was used as the chiral auxiliary in controlling the stereochemical outcome of the reaction of the piperidine-containing carbamate 1042 with the 2-silyloxyfuran 1043 (Scheme 130). With trimethylsilyl triflate as Lewis acid catalyst and butyhnethylimidazolinium tetrafluorobo-rate as additive, an 80% yield was obtained as a 9.7 1 mixture in favor of threo-product (—)-1044. After hydrogenation of the double bond, treatment of the intermediate (—)-1045 with sodium methoxide effected rearrangement to the (R,R)-(- -)-l-hydroxyquinolizidin-4-one (- -)-1046 in 93% overall yield. Mitsunobu inversion of the alcohol to the (lS)-epimer (—)-1047 followed by alane reduction of the lactam afforded the quinolizi-din-l-ol (—)-1048. A second inversion at C-1 with cyanide produced the... 

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