Steglich reaction

The Paal-Knorr reaction was also employed by Steglich in likely biomimetic approaches to the marine alkaloids lamellarin L <00CEJ1147> as well as purpurone and ningalin C <00TL9477>. The overall approach employed herein involved initial oxidative coupling of two arylpyruvic acids followed by condensation of the resulting 1,4-diketones with suitable... 

A particularly elegant domino Heck reaction involving 4-bromoindole and bromo(indolyl)maleimide 251 to give N-methylarcyriacyanin A (252) in one operation was reported by Steglich [173]. This alkaloid could also be prepared from triflate 253 in higher yield in a heteroaryl Heck reaction. 

The transition metal-catalyzed domino reactions will undoubtedly have a splendid future which is underlined by the increasing number of publications in this area Steglich et al. presented an approach to arcyriacyanin A via a domino Heck reaction between a bromo(indolyl)maleiimide and 4-bromoindole.1811 The synthesis of 33 -bifurans by Ling et al. was achieved using a novel palladium-catalyzed domino dimerization and subsequent cyclization of acetylenic ketones.1821 Other applications of a combination of Heck reactions for domino processes are the syntheses of aza-heterocydes developed by our group.1831... 

F Weygand, W Steglich, X Boracio de la Lama. On the sterical course of the reaction of oxazol-5-ones with amino-acid esters. Tetrahedron Suppl 8, part 1, 9, 1966. 

Alternative reactions employ coupling reagents such as DCC (Steglich Esterification), preformed esters (transesterification), carboxylic acid chlorides or anhydrides. These reactions avoid the production of water. Another pathway for the production of esters is the formation of a carboxylate anion, which then reacts as a nucleophile with an electrophile (similar reactions can be found here). Esters may also be produced by oxidations, namely by the Baeyer-Villiger oxidation and oxidative esterifications. 

The Steglich Esterification is a mild reaction, which allows the conversion of sterically demanding and acid labile substrates. It s one of the convenient methods for the formation of terf-butyl esters because r-BuOH tends to form carbocations and isobutene after a subsequent elimination under the conditions employed in the Fischer Esterification. 

Another level of refinement regarding in situ acyl group activations is reached when the activated hydroxycarboxylic acid A is converted with additionally added para-(dimethylamino)pyridine, Steglich s catalyst, in an equilibrium reaction into the cor-... 

Kober R, Papadopoulos K, Miltz W, Enders D, Steglich W, Reuter H, Puff H (1985) Synthesis of diastereo- and enantiomerically pure a-amino-y-oxo acid esters by reaction of acyliminoacetates with enamines derived from 6-membered ketones. Tetrahedron 41 1693... 

Conceptually this new three-component reaction resembles the methods applied by Steglich, Enders et al. [8a] and Yamamoto et al. [8b], who treated the preformed iminoesters 26 and 29 at low temperature with the electron-rich olefins 27 and 30, respectively [9]. However, the use of boronic acid derivatives appears to be a versatile method with a great deal of potential. As Petasis and Zavialov note at the end of their paper, unprotected amino acids and peptides, aryl boronic acids, and chiral boronates can also participate in their three component condensation [7a]. Transition metal catalysis also... 

Steglich esterification of a carboxylic acid with 2,2,2-trichloroethanol using DCC-DMAP affords a mild and convenient method for preparing TCE esters [Scheme 6,88],203 More traditional methods involving the reaction of an acid chloride with trichloroethanol in the presence of pyridine have also been used. 

Active BOC-amino acid esters. Steglich et al. originally used reagent 2 to prepare active esters 5 of BOC-amino acids (4). Actually 2 can also be used to prepare BOC-amino adds by way of 3. In fact the two reactions can be combined for a one-pot preparation of activated BOC-amino acid esters (5). Thus 2 on reaction with f-butanol is converted into the activated t-butyl carbonate 3. This compound in combination with 1 equiv. of tetramethylguanidine as base (6, 246) converts an... 

Schrader, T., and Steglich, W., Phosphorus analogs of amino acids. Part 4. Syntheses of unusual 1-aminophosphonic acids via Diels-Alder reactions of diethyl (7V-acyliminomethyl)phosphonates, Synthesis, 1153, 1990. 

Kober, R., and Steglich, W., Reaction of acylaminobromomalonates and acylaminobromoacetates with trialkylphosphites. A simple synthesis of ethyl 2-amino-2-(diethoxyphosphoryl)acetate, Liebigs Ann. Chem., 599, 1983. 

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