Direct Access to Furanosidic Eight‐Membered Ulosonic Esters from cis‐α,β‐Epoxy Aldehydes.

Abstract

Carbohydrates Carbohydrates U 0500Direct Access to Furanosidic Eight-Membered Ulosonic Esters from cis-α,β-Epoxy Aldehydes. -Mukaiyama aldol reaction of cis-α,β-epoxy aldehydes (I) with α-siloxypropenoate (II) in the presence of Lewis acid BF3·OEt2 provides access to bicyclic precursors of octulosonic acids (III)/(IV). The aldol reaction proceeds with syn-selectivity. Similar result is obtained from the threo-analogues of aldehydes (I). As demonstrated for bicyclic compound (IIIb), acidic cleavage of the bicyclic structure provides the octulosonic acid derivatives [cf. (V)], which can be further functionalized. A variety of functionalized bicyclic precursors (IX) is also tested in acidic ring opening. It is shown, however, that the free endocyclic hydroxyl group is crucial for successful ring opening, since derivatives (IX) do not afford the expected octulosonic acid derivatives. -(SUGISAKI, C. H.; RULAND, Y.; BALTAS*, M.; Eur.

A Validated 1H NMR Method for the Quantitation of 5-Hydroxymethyl-2(5H)-Furanone, a Valuable Chemical Intermediate, In a Dichloromethane Extract of Helleborus lividus subsp: Corsicus Leaves from Corsica

“…is structure is in agreement with HMBC correlations. Identification of 5hydroxymethyl-2(5H)-furanone was confirmed by comparison of its NMR data with those reported in the literature [7][8][9][10]. Moreover, we recorded the 1 H and 13 C spectrum of pure (commercial) (S)-5-hydroxymethyl-2(5H)-furanone and the chemical shift values fitted perfectly with those of the main component of the dichloromethane extract.…”