Alkyl Glycosides

During their synthesis of the F-ring (480) of halichondrin B, Yonemitsu and coworkers relied on allylation of the methyl glycoside derivative 478 to deliver 479, which was converted to the target (Scheme 84) [144]. Johnson has carried out a

Scheme 84

highly selective allylation on the nojirimycin analog 481 to provide 482, which was then converted to the indolizine analog 438 (Scheme 84) [145]. Schmidt converted the TCP-protected glucosamine derivative to 484 via a cationic allylation reaction. Compound 485 was then converted to the amino acid analog 486. The ^-selective allylation is noteworthy and is presumably due to the steric bulk of the phthalide-based amino protecting group, (Scheme 84) [146]. Ley et al. found that exposure 487 to stannic chloride furnished a good yield of the disaccharide derivative 488 as a 1:1 mixture of isomers (Scheme 84) [147].

Two groups have prepared C-glycoside analogs of the natural product (+)-hydantocidin via Lewis acid mediated C-glycosidation of the acetal derivative 489 [148]. Sano and coworkers succeeded in converting 490 to the succinimide analog 493 (Scheme 85) [149]. A synthesis of the spirohydrouracil nucleoside analog of (+)-hydantocidin has also appeared [150].

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