Diphenylphosphino benzoic Acid

The residue is dissolved in 1400 mL water and extracted with 400 mL diethyl ether, which is discarded. The aqueous phase is then filtered, acidified to pH 2 with 60 mL concentrated HC1, and extracted with three 200-mL portions of dichloromethane. The dichloromethane solutions are combined, washed with 500 mL water, and evaporated to ca. 125 mL. Methanol, ca. 50 mL, is then added to precipitate the pale-yellow crystalline product (this sometimes requires inducing) which is collected from the cold solution, affording 50 g (49%) of product. The analytically pure sample is obtained by recrystallization of this product from a minimum amount of boiling methanol, mp 175-176°. 

The air-stable, crystalline compound is soluble in halogenated solvents and diethyl ether but less soluble in other solvents. The infrared spectrum in Nujol mull indicates i oh at 3200 cm 1(m), and vco at 1690 cm 1(s) and at 1275 cm (s). This compound can be esterified with diazomethane to the methyl ester, mp 96-97°, which can be used for other syntheses. 

Acknowledgment is made to the donors of The Petroleum Research Fund, administered by the ACS for support of this research. 

Submitted by A. TRENKLE and H. VAHRENKAMP Checked by JOHN SVOBODAt and LEO BREWERt 

The reaction flask is charged under nitrogen with 15.0 g (80mmole) tetramethyldiphosphine disulfide,6 32.3 g (39.0 mL, 160mmole) tributylphosphine, and 1.44 g (80 mmole) distilled water. The mixture is heated to 160-170° under stirring. When the mixture has become homogeneous, the temperature of the oil 

An oven-dried, 3-L, three-neck, round-bottom flask equipped with a Dry ice condenser, a glass-covered magnetic stirbar, and a gas inlet tube is charged with 1.5 L anhydrous liquid ammonia. Next, Dry ice and acetone are added to the condenser. Sodium metal (15.3 g, 0.667 mole) in ca. 1-g pieces is then added to the stirred ammonia which results in a blue-colored solution. Triphenylphos- 

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Sodium pyrazolate and 3,5-dimethylpyrazolate, [( " -cod)Rh(/A-Cl)]2, carbon monoxide, 3-(diphenylphosphino)benzoic acid, or (2-formylphenyl)diphenyl-phosphine give rise to complexes 120 (R = H, Me) and 121 (R = H, Me) [94JOM(469)213]. However, 2-(diphenylphosphino)benzoic acid (the carboxyl group in the ortho position) leads to formation of the mononuclear complexes 122. The products appear to be catalysts for hydroformylation reactions [93MI2]. 

The coordination modes found in Ni11 complexes with 2-(diphenylphosphino)nicotinic acid and its methyl ester and 2-(diphenylphosphino)benzoic acid and its methyl ester are surprising.696 The complex with the benzoic acid derivative shows the expected P,0 coordination with a six-membered chelate ring (252), while the nicotinic acid analogue forms a four-membered chelate ring with P,N binding (251). 

Chiral ligand 5.20 constructed from a chiral diamine 5.18 and 2-(diphenylphosphino) benzoic acid (5.19) was used by Trost and co-workers " for the enantioselective allylic substitutions. 

The checkers isolated the product by standard flash separation chromatography on Bakerflex flash-grade silica. Unreacted 2-(diphenylphosphino)benzoic acid was obtained as the first band, and the product was obtained cleanly as the second band. An unidentified phosphorus compound was detected in the column wash by PNMR. 

The (amide I) second chromatographic band is discarded. The yellow band that remains at the top of the column is removed by elution with CH3CN. Solvent removal gives 1.2g unreacted 2-(diphenylphosphino)benzoic acid. 

For the Pauson-Khand [2+2+1] cycloaddition175 of alkyne, alkene, and carbon monoxide, as well as being promoted by Co2(CO)8, Portnoy et al.176 synthesized a dendronized support modified with 2- and 4-(diphenylphosphino)benzoic acid groups Co2(CO)8 was then incorporated into the support. A notable increase in catalytic activity and selectivity for the intramolecular Pauson-Khand reaction was found for the Co complexes immobilized on the second-and third-generation dendron-functionalized polystyrene, when compared with the analogous nondendronized support. 

A very exciting concept has been developed with the synthesis of ligands which are derived from 2 -(diphenylphosphino)benzoic acid... 

A dendritic spacer of poly(aryl benzyl ether) was used for incorporation of phosphine ligands onto a PS resin support [116,117]. Thus, the condensation of 4-(diphenylphosphino)benzoic acid with Wang resin bearing poly(aryl benzyl ether) (generation 1-3) gave the PS-supported dendritic phosphine 86. Treatment of the dendritic phosphine 86 with Pd(dba)2 in THF afforded the bisphosphine-palladium complex 87 (Scheme 29) [ 118]. The PS-supported palladium complex exhibited a positive dendritic influence on the Heck reaction of bromobenzene with methyl acrylate. 

As an alternative to this electrophilic activation/heterocyclization, Pd(0)-catalyzed intramolecular Tsuji—Trost reactions have been reported for the synthesis of THPs. For instance, in the presence of a Pd(0) complex and Trost s ligand [(R,R)-diphenylphosphino benzoic acid (DPPBA)]... 

The formyl group in 89 was then epimerized to obtain the compound 90, in which the formyl group had the same configiuation as the natural product. When treated in basic medium the mefa-(diphenylphosphino)benzoic acid directing group, was recovered. 

The allylpalladium chloride dimer (1) has also been used for the preparation of an amphiphilic polymer resin starting from an amino-substituted PEG-PS resin, which was functionalized by 4-(diphenylphosphino)benzoic acid. The corresponding complex... 

It is worth mentioning the huge success diphenylphosphino benzoic acid-based ligands (such as 59), first pioneered by Trost and co-workers, have had in AAA reactions.While many C2-symmetrical ligands such as BINAP, DIOP and CHIRAPHOS have proved extraordinarily successful in other asymmetric transformations, their performance in AAA reactions is... 

In another example of the power of amine nucleophiles in the AAA reaction, Trost reported a highly enantioselective route to mannostatin A (77), a specific nanomolar inhibitor of a-D-mannosidase. Once again a desymmetrization strategy was employed, cyclizing meso substrate 75 in an intramolecular AAA reaction to give adduct 76. While other ligands provided inefficient in this task, the diphenylphosphino benzoic acid-based ligand 59 delivered key intermediate 76 in 97% ee, which was subsequently converted to mannostatin A (77). 

Lucas and Burke reported on aPd(0)-catalyzed asymmetric allylic etherification/ desymmetrization of meso substrates by double cyclizations to the bis-THP subunit of phorboxazoles A and B [51]. Based on Trost and Toste s transition state model for the diphenylphosphino benzoic acid (DPPBA) ligand system [52], Burke rationalized that cyclization of tetraol 69 with (/ ,/ )-DPPBA ligand would effect the double cyclization to give the trans-A ring and cts-B ring in bis-THP 70 (Scheme 24). Under optimized cmiditions, tetraol 69 was converted to 70 in 75 %... 

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