A domino pericyclic route to polysubstituted salicylic acid derivatives: four sequential processes from enynones and ketene silyl acetals.

Organic acid induced olefination reaction of lactones.

(Z)-Selective olefination of several lactones with ketene silyl acetals was achieved by the catalysis of carbon acids (C-H acids) having a bis(triflyl)methyl group as an acidic functionality; in particular, the triple carbon acid having three bis(triflyl)methyl groups in phloroglucinol shows an excellent catalytic performance.

Enantioselective thiourea-catalyzed additions to oxocarbenium ions.

Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest en...

A concise synthesis of tubuphenylalanine and epi-tubuphenylalanine via a diastereoselective Mukaiyama aldol reaction of silyl ketene acetal.

We have developed a straightforward and auxiliary-free synthetic route towards tBu-tubuphenylalanine (tBu-Tup) and tBu-epi-tubuphenylalanine (tBu-epi-Tup), which are the key components of tubulysins and their analogs. A Lewis acid-mediated diastereoselective Mukaiyama aldol reaction using silyl ketene acetal and N-Boc-L-phenylalaninal provided γ-amino-β-hydroxyl-α-methyl esters, which were deox...

Enantioselective acylation of silyl ketene acetals through fluoride anion-binding catalysis.

A highly enantioselective acylation of silyl ketene acetals with acyl fluorides has been developed to generate useful α,α-disubstituted butyrolactone products. This transformation is promoted by a new thiourea catalyst and 4-pyrrolidinopyridine and represents the first example of enantioselective thiourea anion-binding catalysis with fluoride.

Carbogallation of alkynes using gallium tribromide and silyl ketene acetals and synthetic application to cross-coupling with aryl iodides.