Dehydrogenative Silylation of Alcohols Under Pd-Nanoparticle Catalysis

Pd-nanoparticle-catalyzed dehydrogenative coupling between various hydrosilanes and alcohols was shown to provide silyl ethers in good and reproducible yields. The synthetic methodology is effective for a wide range of simple and bulky silanes and secondary alcohols, while keeping various other functional groups intact. The procedure also exhibits high selectivity for the silylation of primary versus secondary alcohols in 1,2-diols, and allows the successive silylation of alkynols and hydrogenation of the triple bond to afford Z-alkenols in good yields.     

Transformation of Amides into Esters by the Use of Chlorotrimethylsilane

A mild transformation of various amides and imides into the corresponding esters and diesters in good yields by using chlorotrimethylsilane and alcohols at rt are described. Either primary, secondary, or tertiary amide or imide can be used in this transformation. Primary and secondary alcohols gave better yields than tertiary alcohols.     

Aqueous Media Oxidation of Alcohols with Ammonium Persulfate

Oxidation of series of various primary and secondary alcohols to corresponding carbonyl compounds with ammonium persulfate in aqueous media was described. No over oxidation of primary alcohols to carboxylic acids and secondary alcohols to esters was observed. Under such conditions benzoin was converted to benzoic acid.     

Indium-mediated reaction of trialkylsilyl propargyl bromide with aldehydes: highly regioselective synthesis of allenic and homopropargylic alcohols

High regioselective preparation of either the allenic alcohols or homopropargylic alcohols using the indium-mediated reaction of trialkylsilyl propargyl bromides with various aldehydes has been accomplished. By just changing the silyl groups and the reaction conditions, both the allenic and homopropargylic alcohols can be obtained in high regioselectivities.     

Direct beta-alkylation of secondary alcohols with primary alcohols catalyzed by a CpIr complex

A new catalytic system for beta-alkylation of secondary alcohols has been developed. In the presence of [CpIrCl(2)](2) (Cp = pentamethylcyclopentadienyl) catalyst and base, the reactions of various secondary alcohols with primary alcohols give beta-alkylated higher alcohols in good to excellent yields without any hydrogen acceptor or hydrogen donor. This reaction proceeds via successive hydrogen-transfer reactions and aldol condensation. [reaction: see text]     

A highly efficient TEMPO mediated oxidation of sugar primary alcohols into uronic acids using 1-chloro-1,2-benziodoxol-3(1H)-one at room temperature

Oxidation of various sugar primary alcohols into corresponding uronic acids was demonstrated using 1-chloro-1,2-benziodoxol-3(1H)-one and TEMPO. The reaction proceeds at room temperature in good to excellent yields. Primary alcohols get oxidized selectively over the secondary alcohols under mild reaction conditions.     

Anti-Markovnikov Hydroamination of Racemic Allylic Alcohols to Access Chiral γ-Amino Alcohols

A ruthenium-catalyzed formal anti-Markovnikov hydroamination of allylic alcohols for the synthesis of chiral γ-amino alcohols is presented. Proceeding via an asymmetric hydrogen-borrowing process, the catalysis allows racemic secondary allylic alcohols to react with various amines, affording enantiomerically enriched chiral γ-amino alcohols with broad substrate scope and excellent enantioselectivities (68 examples, up to >99 % ee).     

One-pot sequential deoximation and allylation reactions of aldoximes in aqueous solution

A simple procedure has been developed for conducting tin-mediated deoximation and allylation reactions of aldoximes in water to form homoallylic alcohols. Employing the new conditions, various homoallylic alcohols were produced in good to excellent yields.     

Gold(III)-catalyzed direct nucleophilic substitution of propargylic alcohols

Gold-catalyzed nucleophilic substitution of propargylic alcohols with various nucleophiles (allylsilane, electron-rich aromatics, alcohols, thiols, hydrides, 1,3-dicarbonyl derivatives, sulfonamides) is described under very mild conditions (room temperature in dichloromethane). Preliminary mechanistic investigations suggest a mechanism through a carbocation intermediate. Nucleophilic substitutions on allylic and benzylic alcohols are also described.     

Copper‐Catalyzed Trifluoromethylation of Trisubstituted Allylic and Homoallylic Alcohols

An efficient copper‐catalyzed trifluoromethylation of trisubstituted allylic and homoallylic alcohols with Togni’s reagent has been developed. This strategy, accompanied by a double‐bond migration, leads to various branched CF₃‐substituted alcohols by using readily available trisubstituted cyclic/acyclic alcohols as substrates. Moreover, for alcohols in which β‐H elimination is prohibited, CF₃‐containing oxetanes are isolated as the sole product.     

Metal-free synthesis of 1,2-amino alcohols by one-pot olefin aziridination and acid ring-opening

A one-pot, two-step reaction comprising olefin aziridination and ring-opening of an aziridine intermediate to synthesize 1,2-amino alcohols has been developed. This reaction is suitable for several types of olefin. This methodology allows an efficient and highly stereoselective approach to various 1,2-amino alcohols, readily providing an alternative route to conventional vicinal amino alcohols.     

Direct Arylation/Alkylation/Magnesiation of Benzyl Alcohols in the Presence of Grignard Reagents via Ni-, Fe-, or Co-Catalyzed sp(3) C-O Bond Activation

Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp(3) C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of (n)hexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.     

Tin mediated allylation reactions of enol ethers in water

Under tin-mediated Barbier-type reaction conditions, hydration of enol ethers takes place to form aldehydes that undergo allylation reactions. By using this process, various homoallylic alcohols and 2-halohomoallylic alcohols are produced in good to excellent yields.     

Recent advances in the homogeneous palladium-catalyzed aerobic oxidation of alcohols

The use of palladium catalysts for the oxidation of alcohols to aldehydes and ketones in the presence of various types of reoxidants is well known. Recently, the advantages of using molecular oxygen as the oxidant in the Pd-catalyzed oxidation of alcohols have been explored. The aim of this review is to provide an overview on the most important homogeneous palladium-catalyzed aerobic oxidation of alcohols without a co-catalyst during last decade until the end of 2007.     

硫化钼系催化剂上低碳醇的分布规律

对低碳混合醇的合成机理,有些学者曾提出了一些假说,例如Graves的构想以及Smith和Anderson的模型等。这些假说有的已被实验所验证,成功地描述了催化剂上产物的分布情况,但对于硫化钼系催化剂,由于发展较晚,尚未见到系统的合成机理的研究报道。Schulz-Flory方程(简称S-F方程)是用来解释费托合成烃类产物的分布规律。我们考察了硫化钼系催化剂上醇类产物分布的特点,得出了醇类分布符合S-F分布规律,并推出了适合于醇分布的S-F方程。     

A novel acid-catalyzed C5-alkylation of oxindoles using alcohols

A novel C5-alkylation of oxindoles using alcohols as alkylating agents under acid catalysis is described for the first time. The reactions of various benzylic, allylic and propargylic alcohols are studied to obtain the corresponding 5-substituted oxindoles in good yields.     

Lewis acid-mediated highly regioselective SN2-Type ring-opening of 2-aryl-N-tosylazetidines and aziridines by alcohols

Lewis acid-mediated highly regioselective SN2-type ring-opening of 2-aryl-N-tosylazetidines with alcohols to afford various 1,3-amino ethers in excellent yields with good enantiomeric excess is described. Similar SN2-type ring-opening of chiral 2-phenyl-N-tosylaziridine with various alcohols produces the corresponding nonracemic 1,2-amino ethers in excellent yields and good ee. The mechanism of the ring-opening of aziridines and azetidines via an SN2 pathway is supported by the formation of nonracemic amino ethers.     

Highly efficient catalytic aerobic oxidations of benzylic alcohols in water

A highly efficient catalytic system without transition metals in water has been developed for aerobic oxidations of benzylic alcohols. The newly developed catalyst system could oxidize benzylic alcohols and heteroaromatic analogues with 1 mol % TEMPO as a catalyst and with a catalytic amount of 1,3-dibromo-5,5-dimethylhydantoin and NaNO2 as cocatalysts. Under the optimal conditions, various alcohols could be converted into their corresponding aldehydes or ketones in high yields.     

Facile One-pot Transformation of 2,3-Epoxy Alcohols into Allylic Alcohols

Optically-active allylic alcohols have been frequently used as chiral building blocks for the preparation of optically pure compounds.¹ There are at present various methods for the synthesis of optically active allylic alcohols including the kinetic resolution racemic allylic alcohols,² reductive rearrangement of 2,3-epoxy alcohol by metal, halide and telluium-based chemistry.³ To our knowledge, One-pot Transformation of 2,3-epoxy alcohols into allylic alcohols, especially via epoxy iodides,is limited to Dorta's method³ using a Ph₃P,iodine, imidazole,2,6-lutidine and water system. The original Dorta's method can be successfully applied to the formation of tertiary allylic alcohols, but give unsatisfactory results in formation of secondary allylic alcohols.     

Expanding the application scope of glycosidases using click chemistry

Glycosidase-mediated glycosylation of alkynyl alcohols and azide-containing alcohols was followed by a click reaction, affording various types of triazole glycosides. The activities of triazole glycosides detected in subsequent bioassays show that this procedure is a feasible approach to the development of anti-fungal drugs.