Organoborates formation

It should be noted that 1,1-organoboration of Me3SiC=CMe with Et3B requires harsher conditions 100 °C and 24 h. Bis(trimethylsilyl)ethyne does not react with Et3B, but readily (20 °C) inserts into the 1-boraadamantane core giving rise to an equilibrium mixture containing c. 80% of 92 (Scheme 35). Treatment of this mixture with bis(trialkylstannyl)ethynes leads to the formation of distannane derivatives 93 (R = Me, Et) which seem to be more stable than 92 <2001JOM(620)51>. 

Formation of Carbon-Carbon and Carbon-Heteroatom Bonds via Organoboranes and Organoborates... 

Upon treatment of bis(dimethylsilyl)ethyne 62 with trialkylborane, 1,1-organoboration took place with formation of 63, which by hydrosilylation of the C=C bond of the alkyl group resulted in the formation of the new seven-membered heterocycle 64 (Scheme 13). The presence of the SiH—B bridge in 63 was confirmed unequivocally by IR, 111, 13C, and 29Si NMR spectroscopic evidence <1999AGE124>. Compound 64 was isolated by distillation as a colorless, extremely air-sensitive liquid. 

One of the most versatile routes to siloles, germoles, stannoles, and eventually to plumboles of type 194, allowing for a great variety of substituents in all positions, is provided by 1,1-organoboration of the respective alkyn-l-ylmetal compounds <1995CCR125, 2006HAC188>. The sequence of reactions involved does not fit into the concept of bond formations (Sections 3.17.8.1-3.17.8.3) outlined so far and therefore it is dealt with separately. 

By contrast, some phenolic Mannich bases (314, R = phenolic residue), heated in the presence of organomagnesium in toluene, afford amine elimination with formation of the R -substituted product (316). Analogous behavior is observed with organobor-anes. By this method, the otherwise unfeasible replacement of an amine by alkyl or aryl groups is thus made possible. 

Ueno S, Chatani N, Kakiuchi F (2007) Ruthenium-catalyzed carbon-carbon bond formation via the cleavage of an unreactive carbon-nitrogen bond in aniline derivatives with organoborates. J Am Chem Soc 129 6098-6099... 

The BF2 chelates are hydrolytically stable (the majority of them may be recrystallized from water) whereas the BCI2 chelates are easily hydrolyzed. The boric acid ester complex triptych boroxazolidines are also stable towards hydrolysis as are other aminoalcohol esters. A great number of the boron chelates are colored several spectrophotometric methods are based on chelate formation for the analytical determination of boric acid, organoboric acids and chelating organic compounds. The boron chelates are remarkable for their pharmacological properties as well. Various aspects of the boron chelates have been reviewed. ... 

E.I. Negishi and M.J. Idacavage, Formation of Carbon-Carbon and Carbon-Heteroatom Bonds via Organoboranes and Organoborates, ... 

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