567. Interaction of alcohols and boron trichloride

Abstract

The borate, chloroboronate BCl(0R) 2, and dichloroboronite BCl,*OR, respectively, were rapidly obtained when the appropriate alcohol (n-, iso-, and sec.-butyl, respectively; 3, 2, and 1 mol. for each alcohol) was mixed with boron trichloride (1 mol.) a t low temperature. It is suggested that these products are formed by the broadside 4-centre approaches of reactants. The chloroboronates readily decomposed a t room temperature affording the alkyI chloride, the trialkyl borate, and boron trioxide, but the dichloroboronites decomposed much less readily and then gave alkyl chloride, boron trichloride, and boron trioxide. Probable mechanisms are discussed. Proportionation readily occurred between the trichloride and trialkyl borate, the chloro-esters being formed.Rearrangement to tert.-butyl chloride occurred in the decomposition of the isobutyl chloro-esters ; and tert.-butyl alcohol (3 mols.) rapidly gave tert.-butyl chloride (3 mols.) and boric acid (1 mol.) when mixed with boron trichloride (1 mol.). Dealkylation of tributyl borates (except lert.) by hydrogen chloride was not observed. Even hydrogen bromide reacted but slowly.IN a previous paper ( J . , 1951, 1020) we described experiments on the alcohol-, the alcoholpyridine-, and the ether-boron trichloride systems with special reference to optically active octan-2-01 and 1-phenylethanol, which were considered as useful standards with respect, not only to the degree of reactivity of the alcoholic carbon atom, but also to the steric course. The function of pyridine was explained, and the preparation of a number of trialkyl borates by means of monopyridinoboron trichloride will be described elsewhere. Extending our observations to mixed ethers of the type of n-butyl sec.-butyl ether, we found it necessary to have precise information on the related alkyl dichloroboronites BCl,*OR, and dialkyl chloroboronates BCl(OR),.Apart from work by Wiberg and Sutterlin (2. anorg. Chem., 1931, 202, 1, 22, 31), which concerned only methyl and ethyl compounds, manipulated in an enclosed, low-pressure apparatus, and an observation on diisoamyl chloroboronate by Kinney, Thompson, and Cheney ( J . Amer. Chem. SOC., 1935, 57, 2396, no information was available to us. We therefore turned to the interaction of the isomeric butyl alcohols with boron trichloride and, although we can now see the need for most detailed and protracted study, we feel it desirable to submit resdts obtained so far, because of the interest now being shown in esters containing boron (Cook, Ilett, Saunders, and Stacey, J., 1950, 3125) and in the interaction of ethyl alcohol with such chlorides as zirconium tetrachloride (with correlation to the silicon tetrachloride system) (Bradley, Abd-el Halim, and Wardlaw, J., 1951, 280; cf. Chem. and Ind., 1951, 310, and Gerrard, ibid., p. 463).Addition of boron trichloride (1 mol.) to n-, iso-, and sec.-butyl alcohol (3 mols.) in pentane readily afforded the corresponding trialkyl borate, unaccompanied by alkyl chloride. We

Enabled Process To Synthesize Monobactam 1 for Early Development

“…Indeed, treating 21 with excess BCl 3 in dichloromethane at −5–10 °C cleaved all protecting groups (e.g., t -butyl ester, N -Boc, and two O -benzyl groups) within 1 h. An optimal amount of 10 equiv of BCl 3 ensured reaction completion without significant impact to the product stability and afforded ∼65% pure 1 with numerous minor side products, including monobactam ring-opened impurity ( 25 , Figure ). Although the product directly precipitated out, the reaction mixture was treated with a solution of trifluoroethanol (45 equiv) in MTBE in an attempt to quench excess BCl 3 and break up 1 –boron complex before filtration . The collected solid was set in filter under nitrogen-blowing for a long time and then triturated in MTBE to further remove acidic volatiles.…”

“…Although the product directly precipitated out, the reaction mixture was treated with a solution of trifluoroethanol (45 equiv) in MTBE in an attempt to quench excess BCl 3 and break up 1−boron complex before filtration. 14 The collected solid was set in filter under nitrogen-blowing for a long time and then triturated in MTBE to further remove acidic volatiles. Thus, a 2.27 kg-scale reaction afforded 1.7 kg of crude 1 (63% pure) with a 115% mass recovery for the first scale-up.…”

“…-)methyl)urea Trifluoroacetic Acid Salt(14). To a 100 L reactor were charged trifluoroacetic acid (36.81 kg, 322.9 mol) and anisole(8.05 kg, 56.0 mol).…”

Esterification

“…Boric esters can be made from the trichloride and alcohols in pentane at -10°C. (99). The thioester, B(SMe)3, is from boron tribromide and lead or silver mercaptide (104).…”

Organogermanium Compounds: Part I. The Interaction of Hexamethyldigermoxane and Trimethylmethoxygermane With Boron Trifluoride

“…The lnechanisnl of this decomposition, as outlined below, might involve four-center cyclic transition states of the type proposed for the analogous interaction of boron trichloride and tribromide with alkyl ethers (18) and disiloxanes (19) respectively.…”