Potassium fert-butoxide

When the reaction is run with potassium fert-butoxide in THF at -5°C, one obtains (after hydrolysis) the normal Knoevenagel product (32), except that the isocyano group has been hydrated (16-65). With the same base but with DME as solvent the product is the nitrile (33). When the ketone is treated with 31 and thallium(I) ethoxide in a 4 1 mixture of absolute ethanol and DME at room temperature, the product is a 4-ethoxy-2-oxazoline (34). Since 33 can be hydrolyzed to a carboxylic acid and 34 to an a-hydroxy aldehyde, this versatile reaction provides a means for achieving the conversion of RCOR to RCHR COOH, RCHR CN, or RCR (OH)CHO. The conversions to RCHR COOH and to RCHR CN have also been carried out with certain aldehydes (R = H). 

Potassium /ert-butoxide See Potassium fert-butoxide Acids, etc. 

Benzocyclobutene, Butyllithium, Potassium fert-butoxide Adcock, W. et al., J. Organomet. Chem., 1975, 91, C20... 

Potassium fert-butoxide ions, (CH3)3COK, can be generated similarily. 

Deprotonation of the imidazolium salt [HsTIME - KPEels with three equivalents of potassium fert-butoxide produced the free carbene TIME " " (2 ), which was isolated and fully characterized (28). Addition of one equivalent of 2 to [(CH3CN)4Cu](PF6) affords the copper carbene complex [(TIME ")2Cu2](PF6)2 (2 -Cu)... 

The other way of synthesis of clozapine is from 8-chloro-10,ll-dihydro-5H-dibenzo[b,e]l, 4-diazepin-ll-thione, which is alkylated at the sulfur atom of the dibenzodiazepine ring by 4-nitrobenzylchloride in the presence of potassium fert-butoxide, giving iV-methyl derivative (6.5.8). Reaction of this with A-methylpiperazine gives the desired clozapine (6.5.7) [59]. 

Potassium fert-butoxide, 41, 101 in dehydration of formamides to isocyanides, 41, 101... 

Exercise 14-22 Bromobenzene "reacts rapidly with potassium fert-butoxide in (CH3)2SO (methylsulfinylmethane, dimethyl sulfoxide, DMSO) to give fert-butyl phenyl ether ... 

Exercise 14-24 What products would you expect from the reaction of bromoform, CHBr3, with potassium fert-butoxide in fert-butyl alcohol in the presence of (a) t rans-2-butene and (b) c/s-2-butene ... 

Table 4.4 lists some common bases used in organic chemistry. Although butyl-lithium behaves as a very strong base in many reactions, it also exhibits other chemistry, so it is usually used to prepare other strong bases listed in the table. Lithium diisopropylamide, sodium amide, dimsyl anion, and sodium hydride are often used to prepare the conjugate bases of aldehydes, ketones, and esters for use in reactions. Potassium fert-butoxide is employed when a base somewhat stronger than the conjugate bases of most alcohols is needed. 

The optional site selective metallation of fluorotoluenes158 with the superbasic mixture of butyllithium and potassium fert-butoxide has been applied to the synthesis of the anti-inflammatory and analgesic drug Flurbiprofen.171 3-Fluorotoluene is selectively metallated in the 4-position with LIC-KOR in THF at — 75 °C to afford, after reaction with fluorodimethoxyborane and hydrolysis, the corresponding boronic acid in 78% yield. A palladium-catalyzed coupling with bromobenzene gives the 2-fluoro-4-methylbiphenyl in 84% yield. This four-step sequence can also be contracted to a one-pot procedure with an overall yield of 79%. A double metallation with the superbasic mixture lithium diisopropylamide/potassium tert-butoxide (LIDA-KOR)172 173 is then required to produce flurbiprofen. 

Diisobutyl 2-Propen-l,l-ylideoe TeBurium4 0.87 g (2.4 mmol) of allyl diisobutyl telluronium bromide and 0.27 g (2.4 mmol) of potassium fert-butoxide are placed in a nitrogen-filled vessel. The vessel and 4 ml of dry tetrahydrofuran are cooled to — 78°. With stirring, the tetrahydrofuran is added dropwise to the mixture, stirring is continued for a few minutes, and then a solution of 0.216 g (2 mmol) of bcnzaldehydc in 2 ml of tetrahydrofuran is added dropwise to the ylide. The mixture is allowed to warm slowly to 20°. Work up and column chromatography on silica gel gives diisobutyl telluride and 2-phenyl-3-vinyIoxirane yield 82%. 

The reason is a change in mechanism. Potassium fert-butoxide is a strong enough base (pfC,H 18) to deprotonate the tetrahedral intermediate in the reaction, forming a dianion. Now that the choice is between Me2N" and O2-, the Mc2N has no choice but to leave, giving the carboxylate salt directly as the product. 

V-Tosyl vinyl sulfoximines 211 can be prepared in a one-pot reaction via an in situ Wadsworth-Emmons procedure from S-methyl-S-phenyl-N-tosylsulfoximine by sequential treatment at -78 °C with n-BuLi, potassium fert-butoxide, and diethyl chlorophosphate, followed by addition of an aldehyde and wanning to 0 °C.103 The resulting (V-tosyl vinyl sulfoximines 211 are formed almost exclusively as the ( )-isomer in good overall yields (60-91%). 

Acylated or mesylated aldehyde adducts 301 react with enol silyl ethers 302 to provide products 303, after a phenylsulfanyl migration reaction. Oxidation of compounds 303 with MCPBA followed by heating under mesitylene reflux and acidic hydrolysis afforded 1,3-diketones 304, whereas treatment with potassium fert-butoxide followed by acidic hydrolysis provided 1,4-diketones 305 (Scheme 79)478. 

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