T-BuOH

J-unsaturated ester is formed from a terminal alkyne by the reaction of alkyl formate and oxalate. The linear a, /J-unsaturated ester 5 is obtained from the terminal alkyne using dppb as a ligand by the reaction of alkyl formate under CO pressure. On the other hand, a branehed ester, t-butyl atropate (6), is obtained exclusively by the carbonylation of phenylacetylene in t-BuOH even by using dppb[10]. Reaction of alkynes and oxalate under CO pressure also gives linear a, /J-unsaturated esters 7 and dialkynes. The use of dppb is essen-tial[l 1]. Carbonylation of 1-octyne in the presence of oxalic acid or formic acid using PhiP-dppb (2 I) and Pd on carbon affords the branched q, /J-unsatu-rated acid 8 as the main product. Formic acid is regarded as a source of H and OH in the carboxylic acids[l2]. 

Quininone (2). Potassium melal (10 g, 0 2S at g) was dissolved In t-BuOH (200 mL). The excess o< t-BuOH was removed in vacuum until a dry mobile powder was obtained. A suspension oi t-BuOK and qumlne 1 (32.4 g, O.t mol), benzophenone (91.0 g, 0 5 moQ in PhH (500 mL) was refluxed for 15-18 h under Ng The cooled mixture was poured into ice and extracted with 10% HCI until the HCI was coiortess. The aad extract was washed with EIzO and dripped with stirring into NH4OH and ice Extraction with EI2O, washing of the extract with brme and evaporation of the extract afforded a total of 30-32 g of 2 (95-98%), mp 106-108 C. 

ROH = t-BuOH. BnOH.,FmOH. AdamantylOH. PhC6H4C(M )20H, CHjSOjCHjCHjOH... 

To cleave p-methoxyphenylmethyl (MPM) ethers DDQ (dichlorodi-cyanobenzoquinone)/t-BuOH-CH2Cl2-phosphate buffer (pH 7.0), 4.5 h. 

The related [(3,4-dimethoxybenzyl)oxy]methyl group has been used similarly, except that, as expected, it is more easily cleaved (DDQ, CH2CI2, t-BuOH, phosphate buffer, pH 6.0, 23°, 110 min, 88% yield). ... 

Pyridinium / -toluenesulfonate, t-BuOH or 2-butanone, heat, 80-99% yield. This method also cleaves the MOM ether and has the advantage that it cleanly cleaves allylic ethers that could not be cleaved by Corey s original procedure. 

From an acid chloride t-BuOH, AgCN, benzene, 20-80°, 60-100% yield.Alumina also promotes the conversion of an acid chloride to a t-Bu ester in 79-96% yield. ... 

C1-3,5-(N02)2C5H2N, Pyr, it 115°, t-BuOH. Other esters are also prepared effectively using this methodology. 

B0C)20, t-BuOH or THF, DMAP, 99% yield. This methodology is effective for the preparation of allyl, methyl, ethyl, and benzyl esters as well. ... 

By transesterification of a methyl ester with t-BuOH and sulfated Si02- ... 

This sulfonyl urea, prepared from an amino acid and p-tosyl isocyanate in 20-80% yield, is cleaved by alcohols (95% aq. EtOH, n-PrOH, or /t-BuOH, 100°, 1 h, 95% yield). It is stable to dilute base, to acids (HBr/AcOH or cold CF3CO2H), and to hydrazine. ... 

NaOMe, MeOH, Pyr or /-BuOK, Pyr, t-BuOH. This group is reasonably stable to aqueous NaOH, ammonia, and 80% acetic acid. 

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