Copper-Catalyzed Dehydrative Cyclization of 1-(2-Hydroxyphenyl)propargyl Alcohols with P(O)H Compounds for the Synthesis of 2-Phosphorylmethylbenzofurans

Keggin structure heteropolyacid-catalyzed phosphinylation of secondary propargyl alcohols with phosphine oxides to γ-ketophosphine oxides

Phosphotungstic acid with a Keggin structure as an efficient, simple and green catalyst for the phosphinylation of secondary propargyl alcohols with phosphine oxides to afford γ-ketophosphine oxides with up to 88% isolated yield was developed using dimethyl carbonate as a green solvent. Diaryl- or alkylaryl-substituted propargyl alcohols, and diaryl or arylalkylphosphine oxides could tolerate the system, which reduced the catalyst dosage, and avoided the use of multi-components and toxic solvents. More interestingly, phosphotungstic acid exhibited the best activity when 0.58 moles of water were added per mole of HPWA, elevating the yield from 55% to 85%. An 18O labelled product was afforded using trace H218O instead of H2O, indicating the participation of water in the reaction. Besides, our work underscores the importance and effect of a small amount of water, acting to promote the transformation of secondary propargyl alcohols into enones, which should be the real intermediates of the reaction. A mechanism involving a carbocation, Meyer-Schuster rearrangement and Michael addition of enones was proposed.

Zn-Catalyzed Dehydroxylative Phosphorylation of Allylic Alcohols with P(III)-Nucleophiles

A novel and efficient protocol for the synthesis of diarylallyl-functionalized phosphonates, phosphinates, and phosphine oxides through the zinc-catalyzed dehydroxylative phosphorylation of allylic alcohols with P(III)-nucleophiles via a Michaelis-Arbuzov-type rearrangement is reported. A broad range of allylic alcohols and P(III)-nucleophiles (P(OR)3, ArP(OR)2, and Ar2P(OR)) are well tolerated in this reaction, and the expected dehydroxylative phosphorylation products could be synthesized with good to excellent yields under the optimal reaction conditions. The reaction can be easily scaled up at a gram-synthesis level. Furthermore, through the step-by-step control experiments, kinetic study experiments, and 31P NMR tracking experiments, we acquired insights into the reaction and proposed the possible mechanism for this transformation.

Iron(II)-Catalyzed Bisphosphorylation Cascade Cycloisomerization of γ-Hydroxyl Ynones and Diphenylphosphine Oxides: Synthesis of Highly Substituted Bisphosphorylated Dihydrofuran Derivatives

An iron(II)-catalyzed bisphosphorylation cascade cycloisomerization of readily accessible γ-hydroxyl ynones and diphenylphosphine oxides is described. This strategy provides a variety of valuable polysubstituted bisphosphorylated dihydrofuran scaffolds via the construction of two C-P bonds and one C-O bond within a single procedure. This developed reaction system demonstrates good functional group compatibilities with considerably low catalyst consumption (as low as 1%), which could be further scaled up to gram quantities in satisfactory yields.

Diastereoselective Generation of C2-Azlactonized 2H-Chromenes via Brønsted Acid-Catalyzed Oxo-Cyclization of Propargyl Alcohols

A new Brønsted acid-catalyzed oxo-cyclization of propargyl alcohols with azlactones to synthesize C₂-azlactonized 2H-chromenes has been established that uses 1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (BiNPO₄H) as the catalyst and gives excellent diastereoselectivities (≥19:1 dr) in most cases. This protocol has a high compatibility with various substituents of substrates, offering a catalytic and useful entry to the fabrication of the synthetically important C₂-functionalized 2H-chromene scaffold.

Synthesis of pyrano[3,2-c]quinolones and furo[3,2-c]quinolones via acid-catalyzed tandem reaction of 4-hydroxy-1-methylquinolin-2(1H)-one and propargylic alcohols

Two acid-catalyzed tandem reactions between 4-hydroxy-1-methylquinolin-2(1H)-one and propargylic alcohols are described. Depending mainly on the propargylic alcohol used, these tandem reactions proceed via either a Friedel–Crafts-type allenylation followed by 6-endo-dig cyclization sequence to form pyrano[3,2-c]quinolones or a Friedel–Crafts-type alkylation and 5-exo-dig ring closure sequence to afford furo[3,2-c]quinolones in moderate-to-high yields. The pyrano[3,2-c]quinolones products could be further transformed to tetracyclic 4,9-dihydro-5H-cyclopenta[lmn]phenanthridin-5-one derivatives.

Two acid-catalyzed tandem reactions between 4-hydroxy-1-methylquinolin-2(1H)-one and propargylic alcohols are described.

The Copper-Catalyzed Reaction of 2-(1-Hydroxyprop-2-yn-1-yl)phenols with Sulfonyl Azides Leading to C3-Unsubstituted N-Sulfonyl-2-iminocoumarins

An operationally simple synthesis of Z-configured and C3-unsubstituted N-sulfonyl-2-iminocoumarins (e.g., 8a) that proceeds under mild conditions is achieved by reacting 2-(1-hydroxyprop-2-yn-1-yl)phenols (e.g., 6a) with sulfonyl azides (e.g., 7a). The cascade process involved likely starts with a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. This is followed by ring-opening of the resulting metalated triazole (with accompanying loss of nitrogen), reaction of the ensuing ketenimine with the pendant phenolic hydroxyl group, and finally dehydration of the (Z)-N-(4-hydroxychroman-2-ylidene)sulfonamide so formed.

Phosphine-Catalyzed Chemoselective Reduction/Elimination/Wittig Sequence for Synthesis of Functionalized 3-Alkenyl Benzofurans

An efficient protocol for the construction of functionalized 3-alkenyl benzofurans is demonstrated under metal-free conditions using catalytic amount of phosphine proceeding an intramolecular Wittig reaction. This one-pot reaction initiated by the phospha-Michael addition of phosphine to O-acylated nitrostyrene, in which phosphine was in-situ-generated from the chemoselective reduction of phosphine oxide with PhSiH₃, would provide the phosphorus ylide to result in the aforementioned multifunctionalized benzofuran via O-acylation/nitrous acid elimination/Wittig reaction.

Synthesis of Sulfonylated Heterocycles via Copper-Catalyzed Heteroaromatization/Sulfonyl Transfer of Propargylic Alcohols

An unprecedented copper-catalyzed heteroaromatization/sulfonyl transfer of propargylic alcohols with isocyanide has been developed. 3-Sulfonyl benzofurans and indoles were produced under Cu(I) catalysis in good to high yields. The developed catalytic methodology provides controlled, modular, and facile access to sulfonyl benzoheterocycle scaffolds.

Catalysis and regioselectivity in hydrofunctionalization reactions of unsaturated carbon bonds. Part III

The review addresses the possibility of obtaining Markovnikov and anti-Markovnikov isomers in the reactions of unsaturated hydrocarbons with organophosphorus and organosulfur compounds having P–H and S–H bonds using metal salts or complexes as catalysts.

The bibliography includes 247 references.

Recent Advances in Metal-Catalyzed Heterocyclic C-P Bond Formation

The phosphorus-containing heterocycles are an important class of compounds in organic chemistry. Because of their potential application in many fields, especially, the synthetic pesticides, medicine and catalyst, the phosphorus-containing heterocycles have attracted continuous attention from organic synthesis scientists. The development of efficient and low-cost catalytic systems is of great interest for the construction of heterocycles C-P bond. Usually, the phosphorus-containing heterocycles is prepared via direct carbon-hydrogen (C-H) bond activation or pre-functionalized of heterocycles with phosphorus-hydrogen (P-H) bond of phosphorus compounds reaction by metal-catalyzed. This review summarizes recent progress in the heterocycles C-P bond formation reactions by metal-catalyzed, which mainly focus on the discussion of the reaction mechanism. It aims to provide efficient methods for the future synthesis and application in this field.

Three-Component Reactions of α-Amino Acids, p-Quinone Monoacetals, and Diarylphosphine Oxides to Selectively Afford 3-(Diarylphosphinyl)anilides and N-Aryl-2-diarylphosphinylpyrrolidines

The three-component reactions of α-amino acids, p-quinone monoacetals (or p-quinol ethers), and diarylphosphine oxides have been developed for the synthesis of 3-(diarylphosphinyl) anilides and N-aryl-2-diarylphosphinylpyrrolidines. The transformations may involve the in situ generation of conjugated azomethine ylides or 2-azaallyl anion species from the reaction of α-amino acids and p-quinone monoacetals, which are further trapped by diarylphosphine oxides.

Copper-catalyzed tandem phosphorylative allenylation/cyclization of 1-(o-aminophenyl)prop-2-ynols with the P(O)–H species: access to C2-phosphorylmethylindoles

A novel method to synthesize C2-phosphorylmethylindoles via the carbocation formation initiated tandem phosphorylative allenylation/cyclization of 1-(o-aminophenyl)prop-2-ynols with the P(O)–H species has been developed.

Zinc-catalyzed regioselective C–P coupling of p-quinol ethers with secondary phosphine oxides to afford 2-phosphinylphenols

A highly regioselective C–P coupling reaction of p-quinol ethers with secondary phosphine oxides is developed as a new synthesis method for 2-phosphinylphenols by using Zn(OTf)₂ as the catalyst.

Ruthenium-catalyzed tandem annulation/arylation for the synthesis of unsymmetrical bis(heteroaryl)methanes

A new Ru-catalyzed tandem furan annulation/arylation strategy has been developed to afford unsymmetrical bis(heteroaryl)methanes by a reaction between propargyl amines and indoles. A series of bis(heteroaryl)methanes containing furan and indole as well as indole and imidazopyridine moieties have been synthesized in high yields. The reaction possibly proceeds through furan annulation followed by nucleophilic addition of indole.

Barium-catalyzed C–OH/P–H dehydrative cross-coupling for C–P bond construction

A barium-catalyzed C–OH/P–H dehydrative cross-coupling protocol for the construction of C–P bonds was developed in an environmentally benign manner.

Brønsted acid-catalysed regiodivergent phosphorylation of 2-indolylmethanols to synthesize benzylic site or C3-phosphorylated indole derivatives

A Brønsted acid catalyzed highly regiodivergent phosphorylation of 2-indolylmethanols with diarylphosphine oxides has been established, which provides an efficient protocol for accessing benzylic site or C3-phosphorylated indole derivatives with structural diversity.