Borane chlorobis

DIENES Bis-3-methyl-2-butyl-borane. Chlorobis(cyclopentadienyl)-hydridozirconium. Formylmethylene-triphenylphosphorane. LithioaUyl-trimethylsilane. Methylcopper. Pal-ladium(II) acetate. Palladium(ll) chloride. Tetrakis(triphenylphosphine)-palladium(O). 

A solution of potassium naphthalenide is prepared from 2.0 g (50 mmol) of potassium and 6.4 g (50 mmol) of naphthalene in 40 mL ofTHF. After 1 h at r.t. this mixture is diluted with 10 mL of diethyl ether and 10 mL of petroleum ether (bp 40-60 °C) and cooled to — 120 °C. 4.5 g (25 mmol) of ( )-l-methoxy-3-phenylthio-1-propcne arc added followed by 3.36 g (25 mmol) of chlorobis(l-dimethylamino)borane. This mixture is allowed to warm to r.t. over 3 h the solvents are removed in vacuo and the residue is carefully distilled through a 5-cm column at 10 2 Torr. The distillate, containing also naphthalene, is dissolved in 30 mL of diethyl ether and treated with 2.95 g (25 mmol) of pinacol for 3 h. The crude product is chromatographed over 30 g of basic alumina (activity 1) using petroleum ether (bp 40 -60°C) giving 9.2 g of a mixture of product and naphthalene the yield of product (89% E) is determined to be 60% by H-NMR analysis. Similarly prepared is ... 

The reduction of (alkylamino)haloboranes using hydride reagents can provide a convenient route to (alkylamino)boranes for example, LiA1H4 has been utilized to prepare bis(dimethylamino)borane [23884-11-9] from chlorobis(dimethylamino)borane [6562-41-0] (68). When this same strategy is applied to (bis(trimethylsilyl)amino)chloro((trimethylsilyl)amino)borane [10078-93-0], the expected compound is obtained along with the formation of two... 

REDUCTION, REAGENTS Bis(triphenyl-phosphine)copper tetrahydroborate. Borane-Pyridine. Calcium-Methylamine/ ethylenediaminc. Chlorobis(cyclopenta-dienyl)tetrahydroboratozirconium(IV). Chromium(II)-Amine complexes. Copper(0)-lsonitrile complexes. 2,2-Dihydroxy-l, 1-binaphthyl-Lithium aluminum hydride. Di-iododimethylsilane. Diisobutyl-aluminum 2,6-di-/-butylphenoxide. Diisobutyl aluminum hydride. Dimethyl sulfide-Trifluoroacetic anhydride. Disodium tetracarbonylferrate. Lithium-Ammonia. Lithium-Ethylenediamine. Lithium bronze. Lithium aluminum hydride. Lithium triethylborohydride. Potassium-Graphite. 1,3-Propanedithiol. Pyridine-Sulfur trioxide complex. 

Both bromodicyclohexylboiane and chlorobis-(l,2-dimethylpiopyl)borane were used the main lequirement is that the alkyl group of the halogenoborane have a low aptitude for migration in the presence of iodine. 

A novel route for the generation of trialkylboron-carbene complexes has been reported (34). As summarized in Scheme 4, the intial step of the reaction sequence involves the N-complexation of 1,4,5-trimethylimidazole 38 with BEts to form 39, followed by deprotonation and rearrangement of resulting ionic species to 40. The final step involves methylation with Mel to form the desired triethylboron-carbene complex, 41. Compound 41 was characterized by mass spectroscopy and H-, C-, and B NMR spectroscopy the B NMR chemical shift for 41 S -12.6) appears in the tetracoordinate boron region. The 1,4,5-trimethylimidazole 38 is also the source of an unusual boryl-borane compound, 43 (34). Treatment with BH3 thf, followed by deprotonation with "BuLi, resulted in the formation of the ionic carbene/borane complex, 42. In turn, 43 was produced via the addition of chlorobis(dimethylamino)borane to 42. Compound 43 exhibits B NMR chemical shifts at S -21.8 (BH3) and 8 27.8 (BNMe2). In related work, N-methyl-AT-borane complexes 44 and 45 have been de-... 

Double stereodifFerentiation was used to achieve enantioselective enolborination of chiral ketones by reaction with chlorobis(isopinocampheyl)borane (DIPCl) in the presence of a chiral amine [69]. As an example, reaction of excess ( )-94 with IPC2BCI and sparteine at —78°C produced 95 regioselectively with a 90% ee (evaluated after oxidation into diadds). 

DIP-Cl is also known to cleave me o-epoxides in an enantioselective manner to generate synthetically important vicinal halohydrins. A recent investigation " shows that the enantiomeric excess achieved with 5-chlorobis(2-isocaranyl)borane (DIcr2B-Cl, 78% ee) is significantly higher than that attained with (-)-DIP-Cl (41%), especially for mew-cyclohexene oxide. 

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