Thexylborane Research Articles

Functionalization and cleavage of coordinated dinitrogen via hydroboration using primary and secondary boranes

The reaction of the side-on, end-on ditantalum dinitrogen complex ([NPN]Ta)2(µ-η1:η2-N2)(µ-H)2 (where NPN = PhP(CH2SiMe2NPh)2) with a variety of secondary and primary boranes is reported. With 9-BBN, hydroboration of the Ta2N2 unit occurs via B-H addition, which in turn triggers a cascade of reactions that result in N—N bond cleavage, ancillary ligand rearrangement involving silicon group migration, and finally elimination of benzene from the N-Ph group and a B-H moiety to generate the imide–nitride derivative. In the presence of excess 9-BBN, the Lewis acid – base adduct of the imide–nitride ([NPµ–N]Ta(=NBC8H14)(µ-NB(H)C8H14)Ta[NPN]) is formed. A similar set of reactions is observed for dicyclohexylborane (Cy2BH), which hydroborates the dinitrogen complex to generate [NPN]Ta(H)(µ-η1:η2-NNBCy2)(µ-H)2Ta[NPN], followed by loss of H2 and silicon group migration to yield the imide–nitride [NPµ–N]Ta(=NBCy2)(µ-N)(Ta[NPN]. With thexyl borane (H2BCMe2CHMe2), a similar sequence of reactions is suggested starting with hydroboration to generate [NPN]Ta(H)(µ-η1:η2-NNB(H)C6H13)(µ-H)2Ta[NPN], followed by loss of H2 and ancillary ligand rearrangement. When bis(pentafluorophenyl)borane (HB(C6F5)2) is used, no hydroboration of coordinated N2 is observed, rather simple adduct formation to give ([NPN]Ta)2(µ-η1:η2-NN-B(H)(C6F5)2)(µ-H)2 occurs. Key words: dinitrogen, tantalum, hydroboration, N—N bond cleavage.

Gelation of Styrene-Acrylonitrile Copolymer via Cyclodiborazane Formation

An azeotropic copolymer of styrene and acrylonitrile was studied with its gelation process via the cyclodiborazane formation between thexylborane (TB) and the cyano groups of the copolymer in 2-methoxyethyl ether solution. The concentrations of TB, cyano groups, and iminoborane were in situ determined by infrared spectroscopy. In addition, the number density of cross-links, i.e., the concentration of cyclodiborazane was quantitatively estimated after the treatment with methanol, which reacts with the B-H groups of TB and iminoborane without decomposition of cyclodiborazane. The number of cross-links was found to increase with reaction time, reaching about 3 per chain at the gel point for the copolymer used in this study.

Macroazoinitiators for the Preparation of Polymers with Cycloborazane Units

Macroazoinitiators containing cyclodiborazane moieties and various amounts of -N=N- units in the main chain were prepared by polyaddition between thexyl borane and adipoyldinitrile (AD) with the addition of 2,2'azobis(isobutyronitrile) (AIBN) at room temperature. These polymers were employed in the polymerization of styrene (St) to afford polystyrene with cyclodiborazane groups.

Hydroboration-carbonylation of bisolefinic amines: a facile synthesis of δ-coniceine

Treatment of N-allyl-N-3-butenyl-N-Cbz-amIne ( 1 ) with thexyl borane followed by cyanidation affords an azacyclononanone 2 in 35% yield which can be transformed into δ-coniceine ( 3 ) by catalytic reduction.

An improved synthesis of monoalkylborane derivatives via bis(thexylborane)-N,N,N',N'-tetramethylethylenediamine

An improved synthesis of monoalkylborane derivatives via bis(thexylborane)-N,N,N',N'-tetramethylethylenediamine

ChemInform Abstract: ORGANOBORANES IN ORGANIC SYNTHESIS. IX. CARBONYLATION PRODUCTS OF ORGANOBORANES DERIVED FROM MYRCENE

Abstract Myrcene and thexylborane react in the ratio 2 3 to give a mixture of two boranes, only one of which is carbonylated with cyanide/trifluoroacetic anhydride, followed by oxidation, to give 3-hydroxymethyl-6-isopropyl-2-methylcyclohexanone (A). The positions of hydroboration are established by synthesis of the hydroboration/oxidation products. The cyanidation of the organoboranes derived from myrcene and diborane leads to a 2 3 mixture of A and 5-(2′-hydroxyethyl)-2-isopropylcyclohexanone, the structures of which are established by independent synthesis. The hydroboration of myrcene is shown to be relatively non-stereospecific.