97782-97-3

Upstream product

• 1692-26-8 bis(propan-2-yl) phenylboronate 
• 1888-75-1 isopropyllithium 
• 75-36-5 acetyl chloride 
• 5419-55-6 Triisopropyl borate 

Relevant academic research and scientific papers

Process for lithium mono- and diorganylborohydrides

Improved processes for liberating boronic, RB(OR')2, and borinic, RR'BOR', esters from their "ate" complexes, free of alcohol are provided. Pyrolysis of lithium organylborates LiRB(OR')3 and LiRR'BOR', wherein R is an organyl group and R' is straight or branched-chain lower alkyl, directly yields the relatively volatile boronic and borinic esters in high purity, leaving behind a residue of lithium alkoxide. Treatment of the lithium organylborates with an appropriate acid halide cleanly liberates either volatile or non-volatile boronic or borinic esters, readily separated from the lower alkyl ester produced as a by-product. The novel compound lithium dimethylborohydride is also provided.

Organoboranes. 48. Improved procedures for the preparation of boronic and borinic esters

Two improved procedures for liberating boronic, RB(O-i-Pr)2, and borinic, RR′BO-i-Pr, esters from their ate complexes, free of isopropyl alcohol, have been developed. Pyrolysis of lithium organylborates, LiRB(O-i-Pr)3 and LiRR′B(O-i-Pr), directly yields the relatively volatile boronic and borinic esters in high purity, leaving behind a residue of lithium isopropoxide. Treatment of the lithium organylborates with appropriate acid chlorides, usually acetyl or benzoyl, cleanly liberates either volatile or nonvolatile boronic or borinic esters, readily separated from the isopropyl ester produced as a byproduct. These developments greatly facilitate the preparation of boronic and borinic esters in high purity.

Organoboranes. 40. A simple preparation of borinic esters from organolithium reagents and selected boronic esters

Monoorganyldiisopropoxyboranes, RB(O-i-Pr)2, react cleanly at -78 °C with 1 equiv of organolithium compounds, R′Li, to form the corresponding complexes of the borinic acid esters, LiRR′B(O-i-Pr)2. Treatment of these complexes with an equivalent of anhydrous hydrogen chloride in ethyl ether liberates the borinic esters, RR′BO-i-Pr, and isopropyl alcohol, usually readily separated by distillation. Alternatively, treatment of the complexes with 1 mol of an appropriate acid chloride liberates the borinic esters, RR′BO-i-Pr, and an isopropyl ester, RCO2-i-Pr. By careful selection of the acid chloride, these two products can be easily separated by distillation. A careful examination of the reaction of other boronic esters in this reaction revealed that the boronic esters of 1,3-propanediol forms the 1:1 complex cleanly on reaction with organolithium compounds at -78 °C. (Formula Presented) Treatment of these ate complexes either with hydrogen chloride in ether or with an appropriate acid chloride provides the pure borinic ester. Consequently, simple rational procedures are now available for the synthesis in high purities and yields of either boronic or borinic acids and esters, either through hydroboration or through the use of organolithium compounds.