Reduction of esters by lithium

The carboxylic acids of the 1,2,4-triazole series are readily decarboxylated on heating, but otherwise stable. Esters, amides and hydrazides react normally. Reduction of esters by lithium aluminum hydride affords triazolylmethanols. 

For reduction, lithium borohydride [38] has an advantage over sodium boro-hydride, as it is readily soluble in simple ether solvents. Lithium borohydride reduces selectively the esters in the presence of other reducible groups. The reduction of esters proceeds smoothly but relatively slowly. However, it is found [39] that in the presence of 10 mol% of lithium-9-boratabicydo[3.3.1]nonane, Li 9-BBNH, or lithium triethylborohydride, LiEtjBH strongly catalyzes the reduction of esters by lithium borohydride in diethyl ether. Catalytic effects have also been observed with B-OMe-9-BBN, LiB(OMe)2-9-BBN, and LiEt3BOMe (Table 25.12) [39]. 

Table 25.13 Reduction of esters by lithium borohydride in refluxing ether in the presence of B-methoxy-9-BBN or methyl borate [39]...

---