Di-iso-butylaluminium hydride

TIBA = tris-iso-butylaluminium DIBAH = di-iso-butylaluminium hydride BEM = n-butylethylmagnesium. xs = excess (3mmol L" ). 

Racemic butyl (a-hex-2-enopyranosid)uronates and the disaccharide derivative (331) have been synthesized by the simple reactions outlined in Scheme 54. Syntheses of DL-desosamine and DL-chalcose from parasorbic acid (332) have been mentioned in Chapters 8 and 11, respectively. Reduction of (332) with di-iso-butylaluminium hydride gave 2-hydroxy-6-methyl-5,6-dihydro-27/-pyran, which afforded the 2-alkoxy-6-methyldihydropyrans (333) on treatment with a molar... 

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