One-pot synthesis of hydrazine derivatives from aldehydes via radical addition reactions

A one-pot procedure for the synthesis of hydrazine derivatives from aldehydes via radical addition reactions was developed. Lewis acids promoted both the condensation between aldehydes and benzhydrazide, and the alkyl radical addition to the Cdbnd?N bond of hydrazones, affording moderate-to-high yields of hydrazine derivatives. The present process provides a tin-free radical, sustainable, and eco-friendly synthetic method.     

One-pot reductive amination of aldehydes catalyzed by a hydrio-iridium(III) complex in aqueous medium

A combination of sodium tetrakis[3,5-di(trifluoromethyl)phenyl]borate [NaBAr^F₄] and hydrio-iridium(III) complex efficiently catalyzed the one-pot reductive amination of aldehydes with various amines and ammonia in water under mild conditions in good to excellent yields.     

One-pot two-step conversion of aromatic carboxylic acids and esters to aromatic aldehydes via indium-catalyzed reductive thioacetalization and desulfurization

Described herein is that a new approach to a one-pot two-step conversion of aromatic carboxylic acids/esters to aromatic aldehydes, in which indium(III) iodide effectively catalyzes both the first reductive thioacetalization of carboxylic acids and a subsequent desulfurization of the in-situ formed thioacetal intermediates leading to aldehydes.     

Iron triflate catalyzed reductive amination of aldehydes using sodium borohydride

An efficient and convenient procedure for the reductive amination of aldehydes using NaBH₄ in the presence of catalytic amount of Fe(OTf)₃ is described.     

The ruthenium catalyzed N-alkylation and N-heterocyclization of aniline using alcohols and aldehydes

Aniline reacts with saturated and 2,3-unsaturated alcohols in the presence of ruthenium catalyst at 180°C to give N-alkylanilines and 2,3-alkylquinolines in good yields.     

Rhodium-catalyzed reductive aldol reactions using aldehydes as the stoichiometric reductants

Chelated acyl rhodium hydrides, generated from the addition of [Rh(dppe)]ClO4 to beta-sulfide-substituted aldehydes, can function as the stoichiometric reductants in reductive aldol processes. Unsaturated nitriles, esters, and ketones can be used as enolate equivalents, and a variety of simple alpha- and beta-substituted aldehydes can be employed. The use of a second, more electrophilic, aldehyde allows three-component reactions to be performed.     

One-pot oxidative esterification and amidation of aldehydes

During recent years, the direct transformation of aldehydes into esters or amides has developed into a vigorous research area and powerful one-pot oxidative esterification and amidation procedures have been reported. Several concepts that are often complementary in substrate scope, functional group tolerance, and reaction outcome have emerged, thus providing a wide range of alternatives to classical ester and amide synthesis via carboxylic acid intermediates.     

Stereoselective three-component synthesis of trans-endo-decahydroquinolin-4-one derivatives from aldehydes, aniline, and acetylcyclohexene

The diastereoselective synthesis of trans-endo-decahydroquinolin-4-one (4) via a three-component reaction of aldehydes (1), anilines (2), and 1-acetylcyclohexene (3) in the presence of iodine in a one-pot reaction at room temperature is described. The short reaction time, easy workup, excellent yield, and mild reaction conditions make this novel annulation strategy both practical and attractive.     

One-pot reductive amination of aldehydes and ketones with α-picoline-borane in methanol, in water, and in neat conditions

A one-pot reductive amination of aldehydes and ketones with amines using α-picoline-borane as a reducing agent is described. The reaction has been carried out in MeOH, in H₂O, and in neat conditions in the presence of small amounts of AcOH. This is a highly efficient and mild procedure that is applicable for a wide variety of substrates. In particular, this is the first successful demonstration that this type of reaction can be carried out in water and in neat conditions.     

Involvement of proton transfer in the reductive repair of DNA guanyl radicals by aniline derivatives

The most easily oxidized sites in DNA are the guanine bases, and major intermediates produced by the direct effect of ionizing radiation (ionization of the DNA itself) are electron deficient guanine species. By means of a radiation chemical method (gamma-irradiation of aqueous thiocyanate), we are able to produce these guanyl radicals in dilute aqueous solutions of plasmid DNA where the direct effect would otherwise be negligible. Stable modified guanine products are formed from these radicals. They can be detected in the plasmid conversion to strand breaks after a post-irradiation incubation with a DNA base excision endonuclease enzyme. If aniline compounds are also present, the yield of modified guanines is strongly attenuated. The mechanism responsible for this effect is electron donation from the aniline compound to the guanyl radical, and it is possible to derive rate constants for this reaction. Aniline compounds bearing electron withdrawing groups (e.g., 4-CF3) were found to be less reactive than those bearing electron donating groups (e.g., 4-CH3). At physiological pH values, the reduction of a guanyl radical involves the transfer of a proton as well as of an electron. The mild dependence of the rate constant on the driving force suggests that the electron is not transferred before the proton. Although the source of the proton is unclear, our observations emphasize the importance of an accompanying proton transfer in the reductive repair of oxidative damage to guanine bases which are located in a biologically active double stranded plasmid DNA substrate.     

One-pot, two-step conversion of aldehydes to phosphonyl- and sulfonylpyrazoles using bestmann-ohira reagent

A one-pot, two-step, three-component method for the conversion of commercially available aldehydes to phosphonylpyrazoles has been developed, demonstrating, for the first time, the dual reactivity of the Bestmann-Ohira reagent (BOR) in a single-pot transformation. This method, extended to the synthesis of sulfonylpyrazoles by employing BOR in the first step and a diazomethyl sulfone in the second step, is complementary, with regard to regioselectivity, to the previous methods for the synthesis of such functionalized pyrazoles.     

HPW and supported HPW catalyzed condensation of aromatic aldehydes with aniline: Synthesis of DATPM derivatives

The mesoporous Si-MCM-41 was synthesized by hydrothermal method and various wt.% (20 and 30 wt.%) of HPW were loaded on Si-MCM-41 by wet impregnation method. The synthesized Si-MCM-41 and HPW-loaded catalysts were characterized by XRD, BET surface area, FT-IR, TEM and TGA–DTG techniques. The catalytic activity of the catalyst was tested over the condensation reaction of aniline with various aromatic aldehydes at refluxing temperature under liquid-phase condition, which yields highly commercial product namely diamino triphenyl methanes (DATPMs). The effects of various parameters like catalyst, mole ratio, solvents and substituent effect on the formation of DATPMs were optimized. The catalytic activity of the catalysts showed the following order: H₃PW₁₂O₄₀·nH₂O > H₃PMo₁₂O₄₀·nH₂O > H₄SiW₁₂O₄₀·nH₂O > 20 wt.% HPW/MCM-41 > 30 wt.% HPW/MCM-41 > HM (12) > Hβ (8) > HY (4) > HZSM-5 (15) > Al-MCM-41 (25). The results showed that mole ratio of 4:1 (aniline:aldehyde) gave higher yield than the other mole ratios. Acetonitrile and ethyl acetate shows better activity especially in the supported materials than toluene was used as a solvent. The product thus obtained was analyzed by ¹H NMR, FT-IR techniques.     

One-pot four-component synthesis of tetrahydrofuran derivatives involving an alkyne, an ethylene and two aldehydes via CuCl-mediated reactions of oxazirconacyclopentenes with aldehydes

In the presence of 1 equiv. of CuCl, the reaction of zirconacyclopentenes with 2 equiv. of aldehydes from −78°C to room temperature afforded tetrahydrofuran derivatives in good isolated yields upon hydrolysis with aqueous 3N HCl; oxazirconacycloheptenes, generated in situ from zirconacyclopentenes with one aldehyde, was found to be the reactive intermediate.     

Direct synthesis of ethers from aldehydes and ketones. One-pot reductive etherification of benzaldehydes,alkyl aryl ketones,and benzophenones

Benzyl alcohols formed by the reduction of benzaldehydes, alkyl aryl ketones, and benzophenones with sodium tetrahydridoborate in alcohols undergo in situ etherification with the solvent in the presence of a catalytic amount of HCl. Thus the process may be regarded as one-pot transformation of carbonyl compounds into the corresponding benzyl ethers. The yields of ethers depend on the substituent nature in the aromatic fragment of the initial carbonyl compound and on the alcohol used as reduction medium.     

One-pot synthesis of polysubstituted pyridine derivatives using ketene dithioacetals

Polysubstituted pyridine derivatives were synthesized by the reaction of ketene dithioacetal, 3,3-bis(methylsulfanyl)methylenemalononitrile 1b, with a variety of active methylene compounds in the presence of either sodium hydroxide or potassium hydroxide as a base in DMSO. This reaction was carried out under economical one-pot reaction conditions (cheap catalyst and solvent) and solved the problem of the odor of methanethiol, commonly derived from reactions of ketene dithioacetals. This is a significant enhancement of GSC (green and sustainable chemistry) in the field of ketene dithioacetal chemistry.     

One-pot synthesis of ω-bromoesters from aromatic aldehydes and diols using pyridinium hydrobromide perbromide

A simple and efficient one-pot procedure has been developed for the synthesis of ω-bromoesters from aromatic aldehydes and diols in the presence of pyridinium hydrobromide perbromide (PHPB) and triethoxymethane in which aldehyde reacts first with diol and the product, cyclic acetal, reacts with PHPB to give the final product, ω-bromoesters.     

One-pot synthesis of unsymmetrical triarylamines from aniline precursors

The "one-pot" synthesis of triarylamines from an aniline and two different aryl halides is described. A catalytic system composed of Pd2(dba)3/P(t-Bu)2-o-biphenyl (1) is used to prepare a variety of triarylamines in a single flask by the coupling of an aniline with an aryl bromide and aryl chloride. The synthesis of triarylamines containing a heterocyclic aryl group is also described by employing a one-flask, two-step method. These methods can be used to synthesize both discrete triarylamines and a triarylamine library.     

One-pot synthesis of conjugated alkynenitriles from aldehydes

A method of preparing conjugated alkynenitriles was developed from various aldehydes with CCl₃CN and PPh₃ in the presence of ^tBuLi. The reaction proceeded via α-chlorovinyl nitrile as an intermediate without any side reactions such as chlorination of starting aldehydes.     

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.     

Direct reductive amination of aldehydes and ketones using phenylsilane: catalysis by dibutyltin dichloride

A procedure for direct reductive amination of aldehydes and ketones was developed which uses phenylsilane as a stoichiometric reductant and dibutyltin dichloride as a catalyst. Suitable amines included anilines and dialkylamines but not monoalkylamines.