Special features of the interaction of pyridine and quinoline derivatives, and related compounds with triphenylphosphine

Using pyridine, quinoline, and related compounds as examples, it has been shown that their interaction with triphenylphosphine occurs via different pathways. Reaction of triphenylphosphine with N-vinylisonicotinic acid chloride leads to the mixture of 1,2-bis(triphenylphosphoniumchlorido)ethane and 4-carboxy-2-(triphenylphosphoniumchloridoethyl)pyridine. In the case of α-(N-2-carboxyquinolinylbromido)-β-bromopropionic acid, the reaction with triphenylphosphine proceeds via phosphine attack on the oxygen atom with elimination of quinaldinic acid, and subsequent nucleophilic substitution with the formation of 3-(triphenylphosphoniumbromido) propionic acid bromide.     

An exception to the normal Mitsunobu reaction with phenols; the formation of hydrazones from salicylaldehydes

The reaction of 2-hydroxybenzaldehydes with alkanols in the presence of triphenylphosphine and di-tert-butyl azodicarboxylate (DBAD), under the Mitsunobu reaction conditions, gives rise to the formation of hydrazones as the major products rather than the expected alkyl aryl ethers.     

DDQ-promoted direct C–H amination of ethers with N-alkoxyamides under visible-light irradiation and metal-free conditions

A C(sp³)–N bond forming reaction between N-alkoxyamides and simple ethers has been developed. In the presence of commercially available 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), a variety of N-methoxyamides and ethers undergo this transformation smoothly to deliver the corresponding products in good yields under visible-light irradiation and metal-free conditions at room temperature.     

Aza-Diels-Alder reaction in fluorinated alcohols. A one-pot synthesis of tetrahydroquinolines

Hexafluoroisopropanol and trifluoroethanol are found to promote imino-Diels-Alder reactions of the N-aryl aldimine 1 with alkyl vinyl ethers to afford the corresponding tetrahydroquinolines in good yields without Lewis acid under mild and neutral conditions. The reaction is also efficient in a three component process from aldehyde, amine and vinyl ethers.     

Palladium assisted organic reactions: III. The preparation of di-μ-chlorobis-(N,N-dialkylbenzylamine-2,C,N)dipalladium(II) complexes

The preparation and ¹H NMR spectra of some di-μ-chloro-bis(N,N-dialkylbenzylamine-2,C,N)dipalladium(II) complexes, and the corresponding monomeric triphenylphosphine derivatives are described. A reaction sequence is presented for the cyclopalladation reaction and some improved conditions for the preparation of these complexes are presented.     

Facile conversion of alcohols into their bromides and iodides by N-bromo and N-iodosaccharins/triphenylphosphine under neutral conditions

N-Bromo and N-iodosaccharins in the presence of triphenylphosphine convert alcohols into the corresponding bromides and iodides in good to excellent yields at room temperature under neutral conditions.     

Straightforward conversion of alcohols into dibenzenesulfonimides

The reaction of various alcohols with N-fluorodibenzenesulfonimide and triphenylphosphine leads to the corresponding dibenzenesulfonylated amines in high yields.     

An efficient,rapid and facile procedure for conversion of aldoximes to nitriles using triphenylphosphine and N-halo sulfonamides

N,N,N＇,N＇-Tetrabromobenzene-1,3-disulfonamide （TBBDA）/triphenylphosphine and N,N,N＇,N＇-tetra- chlorobenzene-1,3-disulfonamide （TCBDA）/triphenylphosphine have been introduced as highly efficient systems for the versatile conversion of aldoxime derivatives into nitriles. The process reported here is operationally simple and reactions have been mildly performed in dichloromethane at room temperature.     

A new application of the Mitsunobu reaction in the synthesis of phosphonium salts

The condensation of methanol or primary alcohols with triphenylphosphonium tetrafluoroborate in the presence of ethyl azodicarboxylate and triphenylphosphine in THF at room temperature gives the respective alkyltriphenylphosphonium salts in good yields. The reaction also worked for the conversion of N-acyl-2-hydroxyglycinates into N-acyl-2-triphenylphosphonioglycinates.     

Reaction of N-sulfinyltrifluoromethanesulfonamide with triphenylphosphine and triphenylphosphine oxide

The reaction of N-sulfinyltrifluoromethanesulfonamide with triphenylphosphine and triphenylphosphine oxide or of trifluoromethanesulfonamide with dichloro(triphenyl)phosphorane leads to trifluoro-N-(triphenyl-λ⁵-phosphanylidene)methanesulfonamide, which is hydrolyzed to trifluoromethanesulfonamide and triphenylphosphine oxide via the intermediate trifluoro-N-[hydroxy(triphenyl)phosphoranyl]methanesulfonamide.     

Asymmetric Mukaiyama aldol reaction of silyl enol ethers with aldehydes using a polymer-supported chiral Lewis acid catalyst

Chiral N-sulfonylated α-amino acid monomer (5) derived from (S)-tryptophan was copolymerized with styrene and divinylbenzene under radical polymerization conditions to give a polymer-supported N-sulfonyl-(S)-tryptophan (6). Treatment of the polymer-supported chiral ligand with 3,5-bis(trifluoromethyl)phenyl boron dichloride afforded a polymeric Lewis acid catalyst (16) effective for asymmetric Mukaiyama aldol reaction of silyl enol ethers and aldehydes. Various aldehydes were allowed to react with silyl enol ethers in the presence of the polymeric chiral Lewis acid to give the corresponding aldol adducts in high yield with high levels of enantioselectivity.     

A facile route to N-acetyl α,β-unsaturated γ-lactam derivatives using ethyl acetamidocyanoacetate and dialkyl acetylenedicarboxylate in the presence of triphenylphosphine

The three component reaction of ethyl acetamidocyanoacetate with dialkyl acetylenedicarboxylates and triphenylphosphine leads to phosphorus ylides in good yields. These ylides undergo a 1,2-proton shift, loss of triphenylphosphine, and subsequent intramolecular amidation leads to the formation of N-acetyl α,β-unsaturated γ-lactams.     

Benzylic bromination catalyzed by triphenylphosphine selenide via Lewis basic activation

The synthesis of benzyl bromides was achieved under mild reaction conditions using N-bromosuccinimide as a bromine source and triphenylphosphine selenide as a catalyst. These conditions were compatible with a variety of substrates including boronic esters, protected amines to give imines, and carboxylic acids (to give phthalides when ortho to the benzylic center). A preliminary mechanistic investigation utilizing calculated bond dissociation energies (BDE) is employed to rationalize how a Lewis base can activate a radical mechanism.     

One-pot synthesis of functionalized furamide derivatives via a three-component reaction between an amine, diketene and dibenzoylacetylene in the presence of triphenylphosphine

An effective route to functionalized furamide derivatives is described. This involves reaction of N-alkyl-3-oxobutanamides, derived from the addition of amines to the diketene, and dibenzoylacetylene in the presence of triphenylphosphoine. The reactive 1:1 intermediate obtained from the addition of triphenylphosphine to dibenzoylacetylene was trapped by OH-acids such as N-alkyl-3-oxobutanamide to produce functionalized furamide derivatives.     

Efficient and rapid synthesis of N-substituted isoquinolin-1-ones under mild conditions: Facile access to doryanine derivatives

We describe the simple and efficient synthesis of N-substituted isoquinolin-1-one derivatives. Initiating with the coupling of benzoic acids containing vinyl ethers with different amines, followed by rapid intramolecular cyclization under acidic conditions at room temperature, N-substituted isoquinolin-1-ones were furnished in high yields. The utility of this simple and mild cyclization method was demonstrated through the practical synthesis of natural product doryanine and its analogues.     

Enantioselective aldol reactions of trichlorosilyl enol ethers catalyzed by chiral N,N-dioxides and monodentate N-oxides

Chiral N,N^′-dioxides and monodentate N-oxides were employed as catalysts in catalytic, enantioselective aldol reactions of trichlorosilyl enol ethers. The reactions of acyclic enol ethers using N,N^′-dioxides resulted in the anti-adducts from (E)-enol ethers and the syn-adducts from (Z)-enol ethers. The reactions of cyclic (E)-enol ethers using N,N^′-dioxides gave the anti-adducts, whereas monodentate N-oxides predominantly gave the syn-adducts.     

Facile synthesis of 1,8-naphthalimides in palladium-catalysed aminocarbonylation of 1,8-diiodo-naphthalene

1,8-Diiodo-naphthalene was aminocarbonylated with various primary and secondary amines in the presence of palladium(0) complexes formed in situ from palladium(II) acetate and triphenylphosphine. In the case of primary amines, depending on the amine to substrate ratio, two types of products have been obtained in highly chemoselective reaction: dicarboxamides and N-substituted imides have been formed at high and low amine to substrate ratio, respectively. The reaction tolerates the ester functionality, so that amino acid esters could serve as N-nucleophiles and in this way, naphthalimides possessing stereogenic centre in the N-substituent could be synthesised.     

Diastereoselective synthesis of unsaturated 1,2-amino alcohols from α-hydroxy allyl ethers using chlorosulfonyl isocyanate

Diastereoselective synthesis of 1,2-amino alcohols was achieved from a highly diastereoselective allylic amination reaction of α-hydroxy allyl ethers using chlorosulfonyl isocyanate. Diastereoselectivities varied depending on the stereochemistry of the ethers used and the stability of the carbocation intermediate obtained during the reaction. We propose that this CSI reaction is the results of either a S_Ni or S_N1 mechanism, according to the stability of the carbocation intermediate.     

Copper-catalyzed imination of sulfoxides and sulfides

Sulfoximines and sulfilimines have attracted considerable interest among organic chemists. The Cu(II)-catalyzed imination of sulfoxides and sulfides using various N-fluoro benzenesulfonamides was investigated in this study. The scope of the reaction was demonstrated by using several substituted sulfides and sulfoxides. The flow strategy for the preparation of NH-sulfoximines was also examined. By trapping nitrene intermediates through triphenylphosphine, we found that the reaction was conducted through a metal-nitrene intermediate mechanism.     

Reaction of difluorocarbene with anions from amides and oximes: Synthesis of N-difluoromethyl substituted amides, O-difluoromethylimidates or O-difluoromethyl substituted oximes under phase-transfer catalysis conditions

N-Aryl substituted amides react with chlorodifluoromethane in the presence of concentrated aqueous sodium hydroxide and benzyltriethylammonium chloride (TEBAC) as a catalyst in benzene (phase-transfer catalysis, PTC), affording mixtures of N- and O-difluoromethyl substituted derivatives. Amide anions are involved in this process. The reaction carried out with oximes gives O-difluoromethyl oxime ethers.