Alternative and Expedient Asymmetric Syntheses of l-(+)-Noviose
摘要:
L-(+)-Noviose, the sugar component of the antibiotic novobiocin, was synthesized from readily available non-carbohydrate starting materials relying on stoichiometric and asymmetric processes by two independent methods, comprising six and nine steps, in 27 and 20% overall yields, respectively.
The enantioselective addition of allylstannanes and allylsilanes to alkyl glyoxylates of type 1, catalyzed by chiral (salen)Cr(III) complexes 3, has been studied. We have found that the reaction proceeded smoothly for low loading (1–2 mol %) of (1R,2R)-(salen)Cr(III)BF43a or (1R,2R)-(salen)Cr(III)ClO43c, and allyltributyltin under simple, undemanding conditions, affording (R)-2-hydroxypent-4-enoic