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In this Letter, we describe a practical and highly selective method for the preparation of fluoroaryl ethers and differentially substituted resorcinol derivatives. This synthetic strategy relies on a selective SNAr of substituted difluorobenzene derivatives with various alcohols.

α-Glycosyl azides can be transformed into the corresponding α-glycosyl acetamides with complete retention of configuration via reduction–acylation (Staudinger ligation) reactions using specifically functionalized phosphines. The α-acetamides of per-O-benzylated-fucose, per-O-benzylated-glucose and per-O-benzylated-galactose were selectively synthesized by this process.

The conjugate addition of propionate silylketene acelal 1 to 2-carbomethoxy cyclopentenone is promoted by bis(oxazoline)-Cu(II) complexes with high diastereoselectivity and good enantiomeric excesses. The absolute configuration of the product can be controlled by varying the copper counterion. A catalytic version of the reaction was developed, which gave ketoacid 5a in 72% d.e. and 63% e.e.

The reactions of the Ti ate enolate 1 and the Li enolate 2 with the chiral enone 3 were studied. Both reactions are moderately stereoselective, leading to the synthesis of the 2,3-anti-3,4-anti and the 2,3syn-3,4anti isomers with 78% and 82% selectivity, respectively. The addition of 1 appears to take place via an inverse demand Diels-Alder reaction, rather than a conjugate addition. This finding can explain the different stereochemical behavior of lithium and titanium enolates in the addition to enones.

Statin analogues can be synthesized stereoselectively (diastereomeric ratios up to 4:1) starting from malic acid. The key step involves an unprecedented cis-selective allylation of an α-alkoxy N-acyliminium ion.

Lewis acid catalyzed reaction of silylenolethers with 1 followed by a straightforward nondestructive removal of the chiral auxiliary affords the corresponding aldehydes in good e.e. Compound 1 represents the first effective chiral synthetic equivalent of formyl cation.

The conjugate addition of t-butylpropionate silylketeneacetal 2 to 2-carboxycyclopentenones 3a-b promoted by TADDOL-derived Ti chlorides gives the ketoacid 6 with excellent d.e. and e.e. up to 47%.

Relative stereochemistry (chelation) effectively controls internal stereochemistry (syn-anti) in the addition of thiopropionate equivalents to O-benzyl lactic aldehyde.

MgBr2 mediated addition of Methyl α-methylthio propionate silylketene acetal to α and α,β-alkoxy aldehydes is highly 3,4 syn -selective (18:1). syn -α- methylene-β- hydroxy-∂-alkoxy esters (6) and (8) are synthesized.

BF3 OEt2 mediated aldol condensations of thioester silyl ketene acetals are stereoconvergent, and exhibit high internal (anti) and relative (Cram) diastereoselectivity.

TiCl 4 mediated aldol condensations establish multiple contiguous chiral centers in an almost complete enantio- and diastereoselective way.

isopropylidenetriphenylphosphorane reacts with oxazolidine 4 with excellent π-face selectivity. The title compound is obtained in high optical purity after removal of the chiral auxiliary.