Borate triphenyl

The development of a solvent reaction between triphenyl borate and paraformaldehyde to produce a boron-modified phenolic resin that flowed at usual processing temperatures has been reported.90... 

The optically active catalyst 93, formed from triphenyl borate and (R)-binaphthol, catalyzes the asymmetric reaction of the dienes 94 (R1 = H or Me) with the imines 95 (R2 = Ph, 3-pyridyl or cyclohexyl). The products 96 are formed in greater than 80% ee (equation 56). Treatment of the diene 94 (R1 = H) (Danishefsky s diene) with the chiral imine 97 leads to the diastereomers 98 and 99 in the ratio 99 1 (equation 57)50. 

Aryl borates such as catechol butylborate and triphenyl borate undergo a syn -stereoselective reaction with arylazirines.41 The syn-stereoselectivity was attributed to a transition state where the phenoxide tethered to the boron is transferred intramolec-ularly to the most substituted carbon. The reaction is completed when the phenoxide anion tethered to the boron reacts with the most substituted carbon of the substrate in an intramolecular reaction. 

An equilibrium mixture of 4 and 5 was prepared by the ligand exchange of boron trichloride and triphenyl borate (16) and found to be an effective catalyst.This suggests our effective catalyst may be produced by the in situ rearrangement of 1 to give 4 and/or 5 which then initiates the polymerization. 

Preparation. The reagent is prepared by reaction of trimethylamine with diborane or with borine carbonyl (BHjCO). In a new procedure developed by Ethyl Corp, an activated aluminum powder and aluminum chloride are added to a solution of triphenyl borate in trimethylamine and the mixture is agitated at 180° under 2,000 p.s.i. of hydrogen. 

The first B chemical shielding tensors have been measured. Trimesityl-borane gives an axially symmetric tensor with a span of 121 ppm and a positive skew, while triphenyl borate is characterized by a tensor that is less than 10 ppm wide. Interestingly, the span observed for trimesitylborane corresponds to the known chemical shift range of tricoordinated boron. Both RHF and B3LYP reproduce nicely these experimental findings. The and Se... 

Yamamoto also reported an asymmetric aza Diels-Alder reaction of an imine mediated by a stoichiometric amount of the chiral boron complex 19 which is conveniently prepared in situ simply by mixing a 1 1 molar ratio of optically active binaphthol and triphenyl borate in CH2CI2 at room temperature [22]... 

Trapping the oxy anion from the Pd-induced ring-opening of a 7,8-epoxy-a,p-unsatu-rated ester with triphenyl borate provides allylpalladium species for eventual reaction with nucleophiles. i yn-3-AIkoxy-4-hydroxy-2-alkenoic esters are readily formed. ... 

Asymmetric aza-Diels-Alder reactions.1 This reaction can be effected in 72-90% cc by catalysis with the chiral boron reagent 1, prepared by reaction of (R)-BINOL with triphenyl borate in CH2CI2 at 25°. Thus reaction of an aldiminc and the Danishefsky... 

The intramolecular cyclization route to a specific P-lactam often depends on the availability of a P-aminoester having the required stereochemistry. A review which considers the asymmetric synthesis of p-aminoesters is available (94MI475). Ytterbium promoted addition of benzylamine to 2-alkenoic esters having a stereogenic centre at the y-position (94CL827) and triphenyl borate mediated reaction of chiral imines with silylketene acetals have been utilised to give P-aminoesters stereoselectively (93BMC2337). 

Although trimethyl and triphenyl borates fail even at 200 C to give any diborane with NaBHij in diglyme (7), trialkylboroxines are quite effective in releasing diborane (84), as is dimethyl sulfate (30). Higher boranes such as tetraborane (249) and decaborane (274) also produce B2H0 by interaction with NaBH in glyme. 

In ether or diglyme, triphenyl borate (but not trimethyl borate) produces diborane with either LiAlHi or NaAlHi, although in restricted yield (7, 8). In this case it is essential to add a solution of the aluminum compound to the ester, for no diborane results if the order of addition is reversed. A disadvantage of this reaction is that the metal tetrahydroborate and possibly the heptahydrodiborate occur as byproducts. ... 

The simple hydrides of the group-III metals have not been extensively studied with respect to their ability to reduce boron compounds to diborane, but Adams (2) refers to cin industrial report which records that aliominum hydride is effective. It thus converts triphenyl borate to diborane (182), and its dialkoxy derivatives of formula AlH(0R)2 are also known to reduce the boron halides to the same compound (156). 

C24H26BeMn03P, Triphenylmethylphosphonium 1,1,1-tricarbonyl-4,6-dicarba-l-mangana-closo-nonaborate(1-), 39B, 480 C24H3oBN302f Tetramethylammonium (ethylnitrosolato-0)triphenyl-borate, 46B, 628... 

A chiral boron reagent, derived from equimolar amounts of (R)-or (5)-binaphthol and triphenyl borate, promotes the condensation of chiral imines with t-butyl acetate silyl ketene acetal in high diastereomeric excess (eq 12). ... 

Alkyl-substituted and phenyl-substituted borate anion receptors have been investigated as electrolyte additives in lithium-ion batteries (58). These compoimds, triphenyl borate and trimethyl borate, are shown in Figure 2.12. 

Triphenyl borate shows the formation of a thick surface/electro-lyte interface which inhibits the ion flow and does not protect the electrode from degradation. Although useful at 25°C, triphenyl borate at 60°C results in only 7% capacity after 100 cycles. 

Later on, Ren and Wulff [53] reported that a combination of the chiral catalyst VANOL-B3 29, derived from the reaction of binaphthol derivative VANOL with triphenyl-borate, also afforded good results in the asymmetric catalytic aminoallylation of a series of aromatic, aliphatic, and a,P-unsaturated aldehydes. Catalytic amounts of benzoic acid were required to ensure the formation of the intermediate imines, and the rearranged imines were hydrolyzed in situ to afford the homoaUylic amines (Scheme 40.44). 

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