Potassium /er/.-BUTOXiDE

An elegant procedure for the synthesis of 5//-dibenz[c,e]azepines 14, which is an extension of the procedure outlined at the beginning of this section, has been developed in which the nitrile ylides, generated by the treatment of iV-(2-arylbenzyl)benzimidoyl chlorides 12 with potassium /er/-butoxide, undergo a 1.7-electrocyclization at the adjacent phenyl ring, followed by a hydrogen shift 13 - 14.102... 

Potassium /er/-butoxide See Potassium tert-butoxide Acids, etc. 

See Potassium /er/-butoxide Acids, or Reactive solvents Dicyclopentadienylchromium Alcohols, 3273... 

Bis(2,4-pentanedionato)chromium, 3326 Molybdenum hexamethoxide, 2596 Potassium /er/-butoxide, 1650 Potassium ethoxide, 0861 Potassium methoxide, 0450... 

An interesting example of hydrogenation with hydrogen in the absence of transition metal catalyst is reduction of benzophenone to benzhydrol with hydrogen in /er/-butyl alcohol containing potassium /er/-butoxide at 150-210° and 96-135 atm. Although the yields range from 47 to 98% the method is not practical because of its drastic conditions, and because of a cornucopia of more suitable reductions. 

Reduction of the carhonyl group to methylene is carried out hy Clemmensen reduction [160, 758], hy Wolff-Kizhner reduction [280, 282], or hy its modifications decomposition of hydrazones with potassium /er/-butoxide in dimethyl sulfoxide at room temperature in yields of 60-90% [845], or hy reduction ofp-toluenesulfonylhydrazones with sodium borohydride (yields 65-80%) [811] (p. 134). 

Intramolecular alkylations of y-lactone enolates are merely variants of the examples mentioned in the previous sections (Section 1.1.1.3.2.2.1.). A striking feature of these reactions is their efficiency with mild bases such as l,8-diazobicyclo[5.4.0]undec-7-ene (DBU) or potassium er -butoxide instead of the lithium amides. 

Probl0m 7.51 Potassium /er/-butoxide, K OCMCj, is used as a base in E2 reactions, (a) How does it compare in effectiveness with ethylamine, CHjCH NH (f>) Compare its effectiveness in the solvents fert-butyl alcohol and dimethylsulfoxide (DMSO) (c) Give the major alkene product when it reacts with (CH JjCClCHjCH,. 

Equation 5.2. describes a transformation, where the palladium catalysed Suzuki coupling was used to establish the first carbon-carbon bond between an indole ring and an acetophenone moiety en route to benzo[c]carbazole. The carbacycle was established in a potassium er -butoxide mediated photochemical transformation.2... 

Methyl acetylenecarboxylate (41 R = H, R = Me) reacts with 2-mercaptocyclohexanone in the presence of a catalytic quantity of potassium er -butoxide to give methyl 4,5,6,7-tetr ahy dr obenzo [6] -thiophene-3-carboxylate (42 R = H, R = Me), together with a mixture of the cis and trans isomers of the adduct (43 R = H, R = Me).257 Substituted acetylenecarboxylic acid esters (41 R=Me or Ph, R = Et) behave analogously only the cis adducts (43) are formed in these cases. 

Use of the more bulky potassium /er/-butoxide instead of methoxide resulted in debromination of 95 to yield 84 (72JOC1851). Treatment of dibenzodiazocine 9 with dilute acids afforded spirotetrahydroisoquinoline... 

Heating 3-methylene-2,3-dihydrotellurophene at 50° for one hour with a mixture of potassium /er/.-butoxide, hexamethylphosphoric acid triamide, and THF produced 3-methyl tellurophene1. 

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