Borane, trimethyl

BCjHg, Borane, trimethyl-, 27 339 BClF4lrN2N2P2C H , Iridium(III), chloro-(dinitrogen)hydrido[tetrafluoroborato-(1 - )]bis(triphenylphosphine)-, 26 119 BClF4lrOP2C37H3i, Iridium(III), carbonyl-chlorohydrido[tetrafluoroborato( I — ))-bis(triphenylphosphine)-, 26 117... 

BC3H, Borane, trimethyl-, 27 339 BC7H13, Borane, diethyl-l-propynyl-,... 

Compounds of the type LBH2X can be prepared by the reaction of the appropriate amine borane and hydrogen haHdes or halogens. The synthesis of the trimethyl amine iodoborane [25741-81-5] adduct (eq. 8) yields a precursor for the preparation of the trimethyl amine isocyanoborane [60045-36-5] adduct as shown in equation 9 (15). 

Bis- 2,6,6-trimethyl-bicyclo[3.1.1 yieptyl-(3) -boran (Diisopino-campheyl-boran) mit der absoluten Konfiguration 1 R 2S 3R 5RI2,vgl i t... 

Organoboranes react with a mixture of aqueous NH3 and NaOCl to produce primary amines. It is likely that the actual reagent is chloramine NH2CI. Chloramine itself,hydroxylamine-O-sulfonic acid in diglyme, and trimethyl-silyl azide " also give the reaction. Since the boranes can be prepared by the hydroboration of alkenes (15-16), this is an indirect method for the addition of NH3 to a double bond with anti-Markovnikov orientation. Secondary amines can be prepared by the treatment of alkyl- or aryldichloroboranes or dialkylchlorobor-anes with alkyl or aryl azides. 

Although the allylation reaction is formally analogous to the addition of allylic boranes to carbonyl derivatives, it does not normally occur through a cyclic TS. This is because, in contrast to the boranes, the silicon in allylic silanes has little Lewis acid character and does not coordinate at the carbonyl oxygen. The stereochemistry of addition of allylic silanes to carbonyl compounds is consistent with an acyclic TS. The -stereoisomer of 2-butenyl(trimethyl)silane gives nearly exclusively the product in... 

Chiral (Acyloxy)borane Complex Catalyzed Asymmetric Diels-Alder Reaction (1 R)-1,3,4-Trimethyl-3-cyclohexene-1-carboxaldehyde. 

CHIRAL (ACYLOXY)BORANE COMPLEX-CATALYZED ASYMMETRIC DIELS-ALDER REACTION (1R)-1,3,4-TRIMETHYL-3-CYCLOHEXENE-1-CAR BOX ALDEHYDE (3-Cyclohexene-1-carboxaldehyda, 1,3,4-trlmethyl-, (-)-)... 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

Thermal decomposition of azidoboranes [Eq. (3)], and of [trimethyl-silyl(trimethylsilyloxy)amino]boranes [Eq. (4)], permits a simple synthesis of symmetric iminoboranes RBNR (17-19). A hot tube procedure at about 300°C and 10 Torr turned out to be useful. The iminoborane iPrBNiPr, for example, was prepared at a rate of 10 g/hour by the azidoborane method. No separation problems are met with this method. Handling the liquid reactants of Eqs. (3) and (4) is hazardous. 

A boron analog - sodium borohydride - was prepared by reaction of sodium hydride with trimethyl borate [84 or with sodium fluoroborate and hydrogen [55], and gives, on treatment with boron trifluoride or aluminum chloride, borane (diborane) [86. Borane is a strong Lewis acid and forms complexes with many Lewis bases. Some of them, such as complexes with dimethyl sulfide, trimethyl amine and others, are sufficiently stable to have been made commercially available. Some others should be handled with precautions. A spontaneous explosion of a molar solution of borane in tetrahydrofuran stored at less than 15° out of direct sunlight has been reported [87]. 

Nitro-propen3 In einem Kolben werden 1,14 g (0,01 mol) Allyl-trimethyl-silan in 10 m/ trockenem Di-chlor-methan auf — 78° gekiihlt, innerhalb 20 min 1,33 g (0,001 mol) Nitronium-tetrafluoroborat zuge-geben. Man leitet einen schwachen Stickstoffstrom durch das GefaB um entstehendes Fluor-trimethyl-silan und Trifluor-boran abzufuhrcn. Nach 30 min ist alles Nitronium-Salz vcrschwunden. Man laBt auf 20° erwarmen, zieht das Dichlormethan ab und destilliert i.Vak. Ausbeute 0,7 g (80%) Sdp. 62°/25 Torr (3,25 kPa). 

Heteroatoni groups such as boron or silicon can activate or direct synthetic reactions. Use of such activation has become of major importance in organic syntheses. Examples in this volume are BORANES IN FUNCTIONALIZATION OF DIENES TO CYCLIC KETONES BICYCLO[3.3.1]NONAN-9-ONE and BORANES IN FUNCTIONALIZATION OF OLEFINS TO AMINES 3-PINANAMINE. Use of trimethylsilyl or trimethyl-silyloxy groups to activate a 2-butenone or a butadiene are illustrated by the preparations 3-TRIMETHYLSILYL-3-BUTEN-... 

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