锡-铟促进和微波辐射辅助下醛和炔丙基溴的炔丙基化反应

A rapid and regioselective preparation of homopropargyl alcohols was reported. In the presence of SnCl2C6HsMe3NBr and microwave irradiation, the mixture of tin-indium and propargyl bromide reacted quickly with aldehydes in aqueous media to produce the homopropargyl alcohols exclusively in high yields. For benzaldehydes bearing different substituents, electronic effect of the substituents affected the reaction, the electron-withdrawing groups promoting the reaction and the electron-donating groups impeding the reaction. The reactions of benzaldehydes bearing an ortho substituent group on the phenyl ring with propargyl bromide may yield a mixture of regioisomers （homopropargyl and homoallenyl alcohols） or a single homoallenic alcohol due to the steric effect.     

锡存在下取代的炔丙基溴与醛反应的选择性

报道三甲基硅基和苯基取代的炔丙基溴在锡存在下与醛的反应, 并讨论了反应的选择性。三甲基硅基炔丙基溴与醛的反应产率约为71-84%。产物中丙二烯醇与高炔丙基醇之比在44 :56到25 : 75之间, 苯基炔丙基溴的反应得到了产物丙二烯醇。     

Lead-promoted Barbier-type reaction of aldehydes with propargyl bromides in aqueous media

This paper reports that the reaction of the propargyl bromides with aldehydes promoted by powdered lead in aqueous media.The selectivity and possible mechanism of these reactions are discussed.The yields of products for reaction of propargyl bromide are 31~71%.The ratios of al-lenyl alcohol and homopropargyl alcohol are 1:1.5 to 1:3.The product for reaction of phenyl propargyl bromide is allenyl alcohol and the yields are 52~84%.     

Regioselective Propargylation of Aldehydes with Propargyl Bromide Mediated by Sn-In in Aqueous Media under Microwave Irradiation

Tin-indium were employed in the propargylations of various aldehydes with propargyl bromide in the presence of SnCl2 and C6H5（CH3）3NBr under microwave irradiation to afford the corresponding homopropargyl alcohols exclusively in high yields. All the reactions were completed smoothly in predominantly aqueous media in 200 seconds only.     

Chemo- and enantioselective catalytic addition of propargyl chloride to aldehydes promoted by [Cr(Salen)] complexes

We describe a full account of our study concerning the [Cr(Salen)]-catalysed addition of propargyl halides to aldehydes. Such a procedure allows the synthesis of enantiomerically enriched homopropargyl alcohols in satisfactory yields with enantiomeric excesses (e.e.s) up to 56%. The excellent chemoselectivity for homopropargyl versus homoallenyl alcohol, represents a peculiar characteristic of our process in comparison to other chromium-mediated propargylation reactions.     

2-Amino homopropargyl alcohols from the highly regioselective Ag2CO3-catalyzed nucleophilic openings of alkynyl epoxides by amines

The nucleophilic ring opening of propargyl epoxides by amines based on a silver catalyst is presented. The reaction takes place under mild conditions and features a high regioselectivity to provide an effective method for the synthesis of 2-amino homopropargyl alcohols in moderate to high yields.     

Highly Selective Synthesis of Acetylenic Alcohols Promoted by Metallic Dysprosium in the Presence of Mercuric Chloride

Promoted by metallic dysprosium, carbonyl compounds react smoothly with propargyl bromide to afford the corresponding homopropargylic alcohols in good to excellent yields without observation of allenic alcohols. In addition, this reaction is regioselective and chemoselective.     

镝促进下醛、酮与炔丙基溴及苯基炔丙基溴的高 选择性反应

在金属镝的促进下,醛、酮可与炔丙基溴反应,高选择性高产率地得到相应的高炔丙醇,没有发现连二烯醇的存在。当用苯基炔丙基溴代替炔丙基溴与醛、酮反应时,主要得到了相应的连二烯醇,而没有发现高炔丙醇的存在,由此提出了六元环过渡态的反应机理。     

Reaction of Propargyl Bromide with Aldehydes in the Presence of Metallic Tin. Synthesis of Homopropargylalcohols and Homoallenylalcohols

In the presence of water, metallic tin and propargyl bromide reacted smoothly with aldehydes to give the corresponding homopropargyl alcohols (a) and homoallenyl alcohols (b). High Chemospecifity to bifounctional carbonyl compounds containing -OH, -X and -NO₂ etc. was obtained.     

Microwave assisted synthesis of dihydropyrrole by AgOAc catalyzed intramolecular cyclization reaction of homopropargyl amine

A series of 5-aryl dihydropyrrole was synthesized from the intramolecular cyclization reaction of homopropargyl amine in the presence of AgOAc as catalyst under microwave irradiation reaction conditions. The homopropargyl amine was prepared by the reaction of propargyl bromide with N-tosyl aldimine under a sonochemical Barbier-type reaction condition. Further aromatization reaction of 5-aryl dihydropyrrole in KOtBu/DMSO can afford 2-aryl pyrrole under microwave irradiation reaction conditions.     

Carbon-Carbon Bond Formation Reaction Promoted by Cadmium In Aqueous Media

Promoted by metallic cadmium allylilic and propargyl bromides react smoothly with aldehydes in aqueous DMF to give homoallylic and homopropargyl alcohols in moderate to good yields. It can also promote pinacol coupling of aromatic aldehydes. The metallic cadmium is produced in situ by the reduction of CdCl₂ H₂O with samarium metal.     

Direct access to CF3-propargyl amines and conversion to difluoromethyl imines

Trifluoromethyl aldimines reacted with acetylides in toluene at −78 °C to provide propargyl amines in good yields. From a chiral trifluoromethyl aldimine, the propargyl amines were obtained with excellent diastereoselectivities (de >98%). Trifluoromethyl propargyl amines could be further converted into difluoromethyl imines under basic conditions.     

A practical procedure of propargylation of aldehydes

An operationally simple procedure of propargylation of aldehydes in moist solvent (distilled THF) has been developed through direct addition of propargyl bromide to aldehyde substrates mediated with low valent iron or tin. The metals were spontaneously prepared in situ employing bimetal redox strategy. Using different aldehydes as substrates (3a-k) both these metal mediated reactions took place producing homopropargyl alcohols (4a-k) in good yields in all cases and with high chemoselectivity in most of the cases (Table 1). Due to its efficacy, operational simplicity, performance in moist solvent, and being comprised of the use of inexpensive metal/metal salts, the procedure is practically viable and potentially scalable.     

Chemoenzymatic route to various spirocyclic compounds based on enantiomerically enriched tertiary allylic,homoallylic, and homopropargylic alcohols

A ring closing metathesis (RCM) reaction of dienes and an intramolecular Pauson–Khand (PKR) reaction of enynes derived from tertiary allyl, homoallyl, and homopropargyl alcohol backbones to afford the corresponding spirocyclic dihydrofuran and dihydropyrans and spirocyclic cyclopentenone pyrans, respectively, are described. Cyclopent-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 1a–c have been efficiently resolved via enzymatic resolution with high ee (up to 90%) with 44%, 40%, and 43% chemical yields, respectively. Moreover, the cyclohex-2-ene anchored tertiary allyl, homoallyl, and homopropargyl alcohols 3a–c have also been resolved in the same manner with high ee (up to 97%) and in 42%, 45%, and 49% chemical yields. Enantiomerically enriched dienes derived from tertiary homoallyl alcohols yield the corresponding enantiomerically enriched spirocyclic dihydropyran derivatives via RCM with 74% and 78% chemical yields and with 90% and 97% ee, respectively. Moreover, enantiomerically enriched enynes derived from tertiary homoallyl alcohols afford the corresponding enantiomerically enriched cyclopentenone pyrans with spirocyclic motifs via PKR with 80% and 81% chemical yields, respectively, and as single diastereomers.     

Ligand-accelerated enantioselective propargylation of aldehydes via allenylzinc reagents

An enantioselective propargylation of aldehydes using an allenylzinc reagent generated in situ via a zinc-iodine exchange reaction is described. The enantioselectivity is controlled by addition of a catalytic amount of readily accessible and highly tunable amino alcohol ligand L13. A wide range of aldehydes can be propargylated to afford valuable and versatile homopropargyl alcohols in good to excellent yields with high levels of enantiopurity.     

In-MEDIATED ALLYLATION OF α-KETO ESTERS WITH ALLYL HALIDES*

The chemoselective reaction of α-keto esters with allyl halides, propargyl bromides, and allenyl bromide using indium metal afforded α-hydroxy-γ,δ-unsaturated esters in good to excellent yields under mild conditions.

     

Sonogashira coupling reaction of homopropargyl ether with aryl bromides and synthesis of 2,5-disubstituted 3-bromofurans

This paper presents Sonogashira coupling reaction of aryl bromides with protected homopropargyl alcohols such as tert-butyldimethyl(1-phenylbut-3-ynyloxy)silane and tert-butyldimethyl(1-(2,4-dichlorophenyl)but-3-ynyloxy)silane in piperidine catalyzed by PdCl₂/PPh₃ without copper(I). The coupling products, disubstituted acetylene, are obtained in good or excellent yields. These products can be further used for the synthesis of 2,5-disubstituted 3-bromofurans.     

Reductive cyclization of o-nitrophenyl propargyl alcohols: facile synthesis of substituted quinolines

Reduction of secondary and tertiary o-nitrophenyl propargyl alcohols followed by acid-catalyzed Meyer-Schuster rearrangement gave 2-substituted and 2,4-disubstituted quinolines, respectively. Tertiary propargyl alcohols gave excellent yields of the quinoline derivative, while the yields of quinolines were slightly reduced when secondary propargyl alcohol derivatives were utilized.     

Diastereoselective synthesis of enantioenriched homopropargyl amino alcohols from α-dibenzylamino aldehydes and their use as chiral synthons

Homochiral α-dibenzylamino aldehydes, prepared from the corresponding α-amino acids, react with propargyl bromide and zinc in DMF/THF (1:1) or DMF/Et₂O (1:1) at 20 °C to afford, in good yields and dr, homopropargylic 1,2-amino alcohols. anti Diastereomers were always formed as major products in this reaction. These compounds are versatile intermediates for a variety of synthetic targets: γ-amino-β-hydroxy-ketones, 4-amino-1,3-diols, 1,7-diamino-2,6-diols, and ω-amino-δ-hydroxy esters.     

Reactions of tertiary propargyl alcohols with sodium halides under oxidative conditions

The study of the reactions of tertiary propargyl alcohols with sodium halides under oxidative conditions is presented. With sodium iodide, α-iodoenones were formed, however, with sodium bromide or chloride the α-haloenones were only formed in low yields under anhydrous conditions. Conversely, upon addition of water to the reaction mixtures, α,α-dibromoketones and α,α-dichloroketones were formed in good yields, but α,α-diiodoketones were not observed.