The combination of Mo and cationic Au catalysts dramatically accelerated the rearrangement of diverse propargyl alcohols, which includes a short reaction time, mild conditions, and high product yields. A practical application to the highly challenging primary propargyl alcohols and the N-alkynyl amides is achieved.

Abstractα-Amino acid thiol esters derived from N-protected mono-, di-, and tripeptides couple with aryl, π-electron-rich heteroaryl, or alkenyl boronic acids in the presence of stoichiometric Cu(I) thiophene-2-carboxylate (CuTC) and catalytic Pd 2 (dba) 3 /triethylphosphite to generate the corresponding Nprotected peptidyl ketones in good to excellent yields and in high enantiopurity. Triethylphosphite plays a key role as a supporting ligand by mitigating an undesired palladium-catalyzed decarbonylation-β-elimination of the α-amino thiol esters. The peptidyl ketone synthesis proceeds at room temperature under non-basic conditions and demonstrates a high tolerance to functionality.

[reaction: see text] A versatile approach to ketone synthesis is described. The reaction relies on the palladium-catalyzed, copper diphenylphosphinate-mediated coupling of thiol esters with organostannanes under neutral reaction conditions. This reaction complements the previously described coupling of thiol esters with boronic acids that used dual thiophilic-borophilic activation methodology.

In the last decade, cooperative catalysis has received considerable attention as a powerful synthetic method. [1] Two or more catalysts function simultaneously or sequentially in a single reaction vessel to construct complicated molecules, which provides a means to perform unprecedented syntheses that cannot be achieved by a single catalyst. Various catalytic combinations involving transition metals, organocatalysts, and biocatalysts have been developed thus far. [2] A typical example is the combined use of lipases and transition metals to attain the dynamic kinetic resolution (DKR) of racemic secondary alcohols for producing single enantiomer products in up to 100 % yields, [3] in contrast to the use of lipases alone, which can only achieve maximum yields of 50 %. In this DKR process, the enzymatic enantioselective esterification of racemic alcohols is combined with the transition-metal-catalyzed continuous racemization of optically active alcohols, which remain intact during the enzymatic reaction, through a redox process. However, such cooperative cocatalysis often encounters crucial issues of low compatibility between the lipases and the transition metals. Although intense efforts have been devoted to developing highly active racemization catalysts, [4, 5] only a few ruthenium complexes have met both the requirement of sufficient compatibility with lipases and high racemization activity. [5] We recently reported that a combination of oxovanadium compounds (4 or 5) with lipases accomplished the efficient and direct conversion of racemic allylic alcohols (AE)-1 and (AE)-2 into optically active allyl esters (R)-3. [6] This method featured a unique racemization process wherein 4 (or 5) catalyzed the racemization of (S)-1 with 1,3-transposition of the hydroxy group of 1 or 2, while the lipases effected chemoand enantioselective esterification. This is significantly different from the above-mentioned ruthenium-catalyzed DKRs and offered a synthetic advantage in that both (AE)-1 and (AE)-2 were available as equivalent substrates. However, this method required further improvement in both catalytic activity and compatibility of the oxovanadium catalysts with the lipases. [7,8] Herein, we report the preparation of a novel oxovanadium catalyst (V-MPS) immobilized inside mesoporous silica (MPS) with pores of approximately 3 nm in diameter, which enabled a complete division of the racemization site and the enzymatic reaction site. The combined lipase-V-MPS catalyst is reusable and achieved DKR of a wide range of racemic alcohols with excellent chemical and optical yields (Scheme 1).The immobilization of oxovanadium species inside a solid carrier with microsized pores or multilayered structures [9] enables the minimization of interactions between the oxovanadium species and lipases while maintaining easy access of substrate molecules to the metal center. The solid carrier should be neutral and non-charged in order to exert little adverse effect on the lipases. Among the various potential solid carriers, [10,11] MPS,...

The intramolecular cyclizations of the 3-alkyne-1,2-diols and the 1-amino-3-alkyn-2-ols with a low catalyst loading (0.05-0.5 mol %) of (Ph(3)P)AuCl-AgNTf(2) or (Ph(3)P)AuCl-AgOTf proceeded at room temperature to provide a variety of substituted furans and pyrroles in excellent yields (85-98% yields). This method is also fully applicable to the conversion of several dozen grams of the substrate using only 0.05 mol % each of the Au and Ag catalysts.