New homochiral cyclic diol ligands for titanium alkoxide catalyzed phosphonylation of aldehydes

Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

Herein, we report a Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence between diarylphosphonates or -phosphinates and α-pyridinealdehydes to access valuable phosphoric ester compounds. This transformation provides an extended substrate scope that is complementary to similar previously reported base-catalyzed transformations.

Carbohydrate/DBU Cocatalyzed Alkene Diboration: Mechanistic Insight Provides Enhanced Catalytic Efficiency and Substrate Scope

A mechanistic investigation of the carbohydrate/DBU cocatalyzed enantioselective diboration of alkenes is presented. These studies provide an understanding of the origin of stereoselectivity and also reveal a strategy for enhancing reactivity and broadening the substrate scope.

Organocatalytic Hydrophosphonylation Reaction of Carbonyl Groups

This revision is covering the limited examples reported for a pivotal strategy in the formation of C-P bonds such as the asymmetric organocatalytic hydrophosphonylation of carbonyl groups (Pudovik reaction). The scope and limitations, and the proposed mechanisms for the scarce different possibilities of asymmetric induction are also shown. The recent evolution and future trends of this undeveloped approach are commented.

Carbohydrate-Catalyzed Enantioselective Alkene Diboration: Enhanced Reactivity of 1,2-Bonded Diboron Complexes

Catalytic enantioselective diboration of alkenes is accomplished with readily available carbohydrate-derived catalysts. Mechanistic experiments suggest the intermediacy of 1,2-bonded diboronates.

An Ni–PyBisulidine complex for the asymmetric hydrophosphonylation of aldehydes

A novel Ni–PyBisulidine complex has been developed for the asymmetric hydrophosphonylation of aldehydes.

Facile base-mediated redox transformation: an efficient strategy for the synthesis of α-acyloxyphosphoryl compounds

An efficient one-pot synthesis of α-acyloxyphosphoryl compounds from aldehydes and hydrogen phosphoryl compounds has been developed using a facile base-mediated redox strategy. This redox transformation is applicable to synthesize a wide range of valuable α-acyloxyphosphoryl compounds with high atom- and step-economic efficiency.

Synthesis of non-racemic α-hydroxyphosphonates via asymmetric phospho-aldol reaction

It has been more than 50 years since the first phospho-aldol reactions of dialkyl phosphites were reported. These efficient P-C bond-forming reactions have become the cornerstone of methods for the synthesis of α-hydroxyphosphonates and, by numerous available substitution reactions, the synthesis of other α- and γ-substituted phosphonates and phosphonic acids. Much of the interest in α- and γ-substituted phosphonates and phosphonic acids has been stimulated by reports of their biological activity, which is often dependent upon their absolute and relative stereochemistry. In this chapter, we review diastereoselective and enantioselective additions of dialkyl phosphites to aldehydes and ketones, otherwise called the phospho-aldol, Pudovik or Abramov reactions.

Addition of optically pure H-phosphinate to ketones: selectivity, stereochemistry and mechanism

A stability-controlled diastereoselective addition of a chiral P–H species to ketones afforded P,C-stereogenic α-hydroxyphosphinates in excellent yields and dr.

Highly efficient hydrophosphonylation of aldehydes and unactivated ketones catalyzed by methylene-linked pyrrolyl rare earth metal amido complexes

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.

Organocatalytic enantioselective synthesis of both diastereomers of alpha-hydroxyphosphinates

Racemic alpha-acylphosphinates and formylphosphinate hydrate were used directly as the substrates in a proline derivative-catalyzed cross aldol reaction with ketones. Because of the preexisting phosphorus stereogenic center, a mixture of two diastereomers of the corresponding alpha-hydroxyphosphinates was obtained in this reaction. Good to high enantioselectivities (up to 99% ee) were obtained simultaneously for the two diastereomers in good yields. Good diastereoselectivities were also obtained when the reaction generates an additional carbon stereogenic center.

Catalytic enantioselective Pudovik reaction of aldehydes and aldimines with tethered bis(8-quinolinato) (TBOx) aluminum complex

New chiral tethered bis(8-quinolinolato) (TBOx) aluminum(III) complexes effectively catalyze the addition of phosphites to aldehydes and aldimines to give enantioenriched alpha-hydroxy and alpha-amino phosphonates in high yields and enantioselectivities with unprecedented reactivity (TON =100 as high as 200). The catalyst is optimized with the low catalyst loading of 0.5 - 1.0 mol %. The modular synthesis of the catalyst allows for potential to tune the reaction for maximum catalytic activity. To date there are few examples with broad substrate scopes that can catalyze both aldehydes and aldimines with such high selectivity and no reports utilizing such low catalyst loading.

Synthesis of an Optically Active Al(salalen) Complex and Its Application to Catalytic Hydrophosphonylation of Aldehydes and Aldimines

Optically active aluminum(salalen) complex 2 was newly synthesized in a modular synthetic manner, and it was found to serve as an efficient catalyst for hydrophosphonylation of aldehydes and aldimines, giving the corresponding alpha-hydroxy and alpha-amino phosphonates with high enantioselectivity, respectively. The scope of the hydrophosphonylation was wide, and both aliphatic and aromatic aldehydes and aldimines were successfully used as substrates for the reaction. The potent catalysis of the complex is attributed to its unique structure: it adopts a distorted trigonal bipyramidal configuration which allows the salalen ligand to take a cis-beta-like structure wherein the chiral amino group is located close to the metal center.