•Formal [3+2] annulation of aldehydo-aldoses with allylsilanes is the key reaction.•The THF ring of the dysiherbaine intermediate was stereoselectively constructed.•The formation of the pyran ring was accomplished by cyclization of a triflate.A highly stereoselective synthesis of the hexahydrofuro[3,2-b]pyran core of (−)-dysiherbaine is described. The key step in this synthesis includes the stereocontrolled formation of the tetrahydrofuran ring using the formal [3+2] annulation of the isopropylidene-protected aldehydo-L-arabinose and the β-substituted allylsilane mediated by trifluoroborane etherate.

A practical four-step method for the synthesis of mumefural from malic acid is described. The key step of this method involves the alkylation of acetal-protected malic acid with bromoacetate, followed by condensation with 5-(hydroxymethyl)furfural. Some of the 13C NMR data for our products differed from those previously reported, and further analysis indicated that the previously reported assignments were partly erroneous.

3-Isopurine nucleosides, namely 3-(ribofuranosyl)purine nucleosides, are interesting owing to their potential biological activity and as components of modified oligonucleotides. A regio- and stereocontrolled method was developed for the synthesis of β-2′-deoxy-3-isopurine nucleosides using the intramolecular glycosylation protocol. The availability of this method was shown by the first chemical synthesis of 3-(2-deoxy-β-d-ribofuranosyl)xanthine and isoguanine.

The synthesis of α,γ-diazido-α,β-unsaturated esters is carried out via a Lewis acid-mediated 1,3-diazidation of α,α-dimethoxy-β,γ-unsaturated esters using two equivalents of trimethylsilyl azide. The reaction proceeds in a highly stereoselective manner to provide only the (Z)-stereoisomers of the diazide products. The optimization and scope of the new method are discussed, and the utility of the products is demonstrated in the synthesis of bis-1,2,3-triazole derivatives.

The [3 + 2] annulation of 2,3-O-isopropylidene-aldehydo-aldose with methallyl ether leads to the stereoselective formation of a substituted tetrahydrofuran system, which is converted to a bicyclic lactone derivative via consecutive deprotection, oxidative cleavage of the terminal diol, oxidation of the resulting lactol, and Barton–McCombie deoxygenation. The efficiency of this process was demonstrated by the first total synthesis of Plakortone L.

Intramolecular glycosylation of purine derivatives that are temporarily connected to the 5 position of ribofuranosyl donors at their 8 position through an ethereal linkage leads to 8-oxo-purine β-nucleosides in a stereoselective manner.

The Lewis acid-promoted reaction of β,γ-unsaturated α,α-dimethoxy esters, which are easily prepared by the acetalization of β,γ-unsaturated α-keto esters, with silyl nucleophiles is presented. By employing trimethylsilyl enolate and allyltrimethylsilane as nucleophiles, the BF3-promoted reactions of a series of β,γ-unsaturated α,α-dimethoxy esters bearing aromatic and aliphatic substituents proceeded at the γ-position in an SN2′ manner to furnish γ-substituted α,β-unsaturated α-methoxy esters in good yields with high regioselectivity. In contrast, the reaction using trimethylsilyl cyanide predominantly occurred at the α-position, and the reaction of silyl hydride resulted in a mixture of α- and γ-regioisomers in favor of the γ-substitution products.