From boranes

Monohalogenoboranes are conveniendy prepared from borane—dimethyl sulfide and boron trihahdes (BX where X = Cl, Br, I) by redistribution reaction, eg, for monochloroborane—dimethyl sulfide [63348-81-2] (9) (81—83). Other methods are also known (84—87). 

Alternative high-yield syntheses of these various boranes via hydride-ion abstraction from borane anions by BBra and other Lewis acids have recently been devised l (see p. 162). 

The oxazaborolidines are easily prepared by heating ephedrine with borane dimethyl sulfide or the appropriate boronate ester. The aluminum reagent C is obtained by mixing ephedrine and trimethylaluminum. Borolidinc A is superior to its methyl derivative B and to the aluminum analog C. The diastereomeric borolidine obtained from borane and (S,S)-pseu-doephedrine failed to show any cnantioselectivity25. A variety of aromatic aldehydes can be enantioselectively alkylated in the presence of A, however, with heptanal the enantioselectivity is poor25. 

Formation of Alkynes, Alkenes, and Ketones from Boranes and Acetylides... 

On the other hand, several examples of chiral sulfonamides derived from ehiral a-amino acids have been successfully employed as ligands for enantio-seleetive Diels-Alder reactions. Thus, Yamamoto and Takasu have easily prepared new chiral Lewis acids from borane and sulfonamides of various ehiral a-amino acids, which were further studied for their abilities to promote the enantioselective Diels-Alder reaction between methacrolein and 2,3-dime-thyl-1,3-butadiene. Since 2,4,6-triisopropylbenzenesulfonamide of a-amino-butyric acid gave the highest enantioseleetivity, this eatalyst was applied to the... 

Since the 3-substituent may originate from borane as well as from the solvent [e.g. with triisopropyl borane in diethyl ether indenones 309 were obtained with... 

Yields of B Hio were 75%. This method demonstrates that bromide ion is a good leaving group from borane entities. In subsequent studies by Schaeffer (42) and by Gaines (43), fused borane and linked borane cages were prepared by taking advantage of this property. 

Addition of alane and borane to alkenes affords a host of alkylated alanes and boranes with various reducing properties (and sometimes bizarre names) diisobutylalane (Dibal-H ) [104], 9-borabicyclo[3.3.1]nonane (9-BBN) (prepared from borane and 1,5-cyclooctadiene) [705], mono- [106,107] and diiso-pinocampheylborane (B-di-3-pinanylborane) (both prepared from borane and optically active a-pinene) [108], isopinocampheyl-9-borabicyclo[3.3.1 Jnonane alias B-3-pinanyl-9-borabicyclo[3.3.1]nonane (3-pinanyl-9-BBN) (prepared from 9-borabicyclo [3.3.1]nonane and a-pinene) [709], NB-Enanthrane prepared from 9-borabicyclo[3.3.1]nonane and nopol benzyl ether) [770] and others. ... 

Substituents are named as one of several classes. The most important ones are dealt with here. For monoatomic radicals from borane, methane, silane (and other Group IVA elements) they are named by replacing the ane ending by yl, i.e., ylene and ylidyne, to denote the loss of one, two, or three hydrogen atoms, respectively ... 

Catecholborane (1,3,2-benzodioxaborole) with a purity of 95% was purchased from Aldrich Chemical Company, Inc. and purified by distillation under nitrogen, bp 58°C (52 mm). For the distillation and handling of air and moisture sensitive compounds, see references 3-5. Catecholborane is a liquid at room temperature, and the neat material is 9.0 H in catecholborane. The preparation of catecholborane from borane and catechol has been reported. ... 

Atkah metal hydrides too abstract protons from boranes. While water is produced with basic hydroxides, hydrogen is liberated with hydrides. Except diborane, all other boron hydrides undergo similar reactions, liberating hydrogen ... 

Cleavage of hydroperoxides 8-23 Rearrangement of ethers upon treatment with alkyllithiums (Wittig) 8-24 From boranes and CO, or CN, or CHCEOMe... 

---