One-pot enantioselective synthesis of optically active homoallylic alcohols from allyl halides

A one-pot, convenient method for the preparation of optically active homoallylic alcohols from allyl halides was developed. Allyltrichlorosilanes were generated in situ from allyl halides and trichlorosilane in the presence of cuprous chloride and tertiary amine. Without isolation of the allyltrichlorosilanes, benzaldehyde and chiral biquinoline N,N'-dioxide were introduced into the same flask, producing the corresponding homoallylic alcohols with good to high enantioselectivities.     

A highly enantioselective one-pot synthesis of homoallylic alcohols via tandem asymmetric allyl transfer/olefin cross metathesis

A highly enantioselective one-pot synthesis of linear homoallylic alcohols with terminal ester functionality has been achieved. The reactions were controlled by ordered addition of reagents and catalysts, ensuring complete consumption of aldehyde. The synthetic utility of this strategy has been demonstrated in a short synthesis of a low boiling point intermediate for grahamimycin A.     

Palladium-catalyzed nitromethylation of aryl halides: an orthogonal formylation equivalent

An efficient cross-coupling reaction of aryl halides and nitromethane was developed with the use of parallel microscale experimentation. The arylnitromethane products are precursors for numerous useful synthetic products. An efficient method for their direct conversion to the corresponding oximes and aldehydes in a one-pot operation has been discovered. The process exploits inexpensive nitromethane as a carbonyl equivalent, providing a mild and convenient formylation method that is compatible with many functional groups.     

Magnesia-supported hydroxylamine hydrochloride in the presence of sodium carbonate as an efficient reagent for the synthesis of 1,2,4-oxadiazoles from nitriles

An efficient one-pot method has been developed for the synthesis of 1,2,4-oxadiazoles through a one-pot reaction of nitriles with hydroxylamine hydrochloride in the presence of magnesia-supported sodium carbonate followed by reaction with acyl halides under solvent-free conditions using microwave irradiation. This method is easy, rapid and good yielding.     

Copper-catalyzed tandem reaction directed toward synthesis of 2,2-disubstituted quinazolinones from vinyl halides and 2-aminobenzamides

A copper-catalyzed tandem reaction with vinyl halides and 2-aminobenzamides has been developed. In this synthetic route, cross-coupling reaction of the amide moiety with vinyl halides initially progresses, followed by hydroamination, to provide 2,2-disubstituted quinazolinone derivatives. Moreover, the tandem reaction is used in a one-pot synthesis beginning with alkyne hydroiodination by PPh₃, I₂, and H₂O.     

N-Halo succinimide-promoted one-pot three-component electrophilic cyclization: Facile access to dihalogenated heterocycles under mild conditions

An effective and concise electrophilic cyclization of 1,4-butynediols, 4-aminobut-2-yn-1-ols, pent-2-yne-1,5-diols, 2-propynolphenols and 2-propynolanilines with N-halo succinimides and trimethylsilyl halides opens a one-pot synthetic access to five- and six-membered dihalogenated heterocycles in moderate to good yields. The optimized cyclization conditions are tolerated with many functional groups.     

Stereoselective synthesis of functionalised carbocyclic amides: construction of the syn-(4aS,10bS)-phenanthridone skeleton

A new synthetic approach has been developed for the preparation of 7-deoxypancratistatin analogues bearing a syn-(4aS,10bS)-phenanthridone ring junction. A one-pot tandem process involving a substrate-directed Overman rearrangement and ring closing metathesis reaction was developed for the stereoselective synthesis of a carbocyclic allylic trichloroacetamide. Conversion to a 6-bromopiperonyl amide, followed by a Heck reaction generated a homoallylic alcohol and completed the syn-(4aS,10bS)-phenanthridone carbon skeleton. Stereoselective epoxidation and dihydroxylation of the syn-(4aS,10bS)-phenanthridone framework was then investigated leading to the preparation of new analogues of 7-deoxypancratistatin.     

The NHCs-mediated cross-coupling of aromatic aldehydes with benzyl halides: synthesis of α-aryl ketones

A new NHCs-mediated synthetic method was found to produce α-aryl ketones in 22-63% yields in one-pot process from the corresponding aromatic aldehydes and benzyl halides. This method is the first example of the NHCs-mediated intermolecular nucleophilic acylation of aromatic aldehydes with benzyl halides.     

Ring-closing metathesis as a tool for the efficient preparation of chiral spirocyclic ethers from homoallylic alcohols

The preparation of chiral spirocyclic ethers via allylic etherification/olefin metathesis of homoallylic alcohols is investigated. This reaction sequence transforms the enantiopure substrate alcohols, synthesized by a one-pot asymmetric rhodium-catalyzed conjugate addition/metal-mediated allylation procedure, into the desired spiro ethers with full conversions and in excellent isolated yields. The synthetic sequence provides an efficient means for a rapid construction of functionalized spiro ethers in a stereoselective manner.     

Novel Access to Organostannane Compounds under Ultrasound Irradiation

A simple and efficient procedure has been developed for the synthesis of organostannane compounds by one-pot reaction of stannane halides, magnesium turnings and organic halides in the presence of 1,2-dibromoethane under ultrasound irradiation.     

One-pot allyl-/crotylboration-Prins cyclization of aldehydes

Multi-substituted tetrahydropyrans (THPs) have been prepared via a one-pot, In(OTf)₃-catalyzed, sequential allyl-/crotylboration-Prins cyclization. The homoallylic borate intermediate formed during the allyl- and crotylboration was converted in situ to an oxocarbenium ion and trapped with a nucleophile. The reaction has been extended to include a one-pot allylboration-cross Prins cyclization as well.     

Ruthenium(III) chloride catalyzed efficient synthesis of unsymmetrical diorganyl selenides via cleavage of dibenzyl and diphenyl diselenides in the presence of zinc

[equation: see text] An efficient one-pot route to unsymmetrical diorganyl selenides has been developed by ruthenium(III) chloride catalyzed reactions of dibenzyl or diphenyl diselenides with alkyl halides in the presence of zinc. Organic iodides, bromides, and activated chlorides underwent the reactions efficiently. Unreactive organic chlorides also underwent the same type of selenation with sodium bromide as the additive.     

Suppression of epimerization due to selectivity leakage: an application towards the total synthesis of (−)-centrolobine

An InCl₃-mediated Prins cyclization of homoallylic alcohols with aldehydes has been established. The enantioselectivities of the trisubstituted tetrahydropyrans are almost retained through the suppression of epimerization. The synthetic value of this protocol is demonstrated by the total synthesis of (−)-centrolobine.     

A Novel Access to Organostannane Compounds under Ultrasound Irradiation

A simple and efficient procedure has been developed for the synthesis of organostanane compounds by one-pot reaction of stannane halides,magnesium turnings and organic halides in the presence of1,2-dibromoethane under ultrasound irradiation for the first time.     

A novel isocyanide-based three-component reaction: a facile synthesis of substituted 2H-pyran-3,4-dicarboxylates

An efficient method for synthesis of 2H-pyran-3,4-dicarboxylates using the three-component reaction of dithiocarbamates, dialkyl acetylenedicarboxylates, and isocyanides in solvent-free conditions is described. In these reactions, synthesis of dithiocarbamates is possibly based on the one-pot reaction of secondary amines, CS₂, and alkyl halides in solvent-free conditions without using a catalyst. The mild reaction conditions and high yields of the reaction exhibit the good synthetic advantage of these methods.     

Solution-phase parallel synthesis of highly diverse spiroisoxazolinohydantoins

Practical and efficient solution-phase parallel synthesis of spiroisoxazolinohydantoins under mild conditions has been developed. This spiroisoxazolinohydantoin skeleton possesses three diversity points. The key intermediate, exo-methylenehydantoin bearing two positions of diversification, is prepared via a one-pot synthetic route from N-substituted methyl ester serine. Employing various alkyl halides, isocyanates, and oximes, this chemistry is applied in the generation of an 18-member demonstration library with high yield, high purity and excellent regioselectivity.     

Novel approach to multifunctionalized homoallylic alcohols via regioselective ring opening of aryl oxiranes with 3-iodo allenoates

[reaction: see text] 3-Iodo allenoates were generated in situ and utilized, for the first time, in the ring opening of oxiranes in a regioselective fashion. This simple one-pot three-component reaction protocol provides easy access to highly functionalized homoallylic alcohols in good yields and moderate to very good (Z/E) selectivity. The two functional groups (ester and halogen) can be further subjected to many synthetic transformations.     

Stereoselective synthesis of trisubstituted olefins through 2,5-dialkylidenemagnesacyclopentanes

An efficient one-pot procedure for the synthesis of trisubstituted olefins with Z-configured double bonds has been developed on the basis of cross coupling of 2,5-dialkylidenemagnesacyclopentanes (generated in situ) with alkyl, allyl, and aryl halides in the presence of transition metal (Cu, Zr, Fe, Co, Ni, Pd) salts and complexes.     

A facile one-pot synthesis of N-substituted tetrahydroquinolines

An uncatalyzed one-pot synthesis of N-substituted tetrahydroquinolines was achieved in good yields by the reaction of quinoline and alkyl/acyl halides with Hantzsch dihydropyridine ester under mild reaction conditions.     

Synthesis of 8-arylquinolines via one-pot Pd-catalyzed borylation of quinoline-8-yl halides and subsequent Suzuki-Miyaura coupling

A one-pot process has been developed for the synthesis of 8-arylquinolines via Pd-catalyzed borylation of quinoline-8-yl halides and subsequent Suzuki-Miyaura coupling with aryl halides using n-BuPAd(2) as ligand. Yields of up to 98% were obtained.