Strecker amino acid

Miscellaneous Reactions. Sodium bisulfite adds to acetaldehyde to form a white crystalline addition compound, insoluble in ethyl alcohol and ether. This bisulfite addition compound is frequendy used to isolate and purify acetaldehyde, which may be regenerated with dilute acid. Hydrocyanic acid adds to acetaldehyde in the presence of an alkaU catalyst to form cyanohydrin the cyanohydrin may also be prepared from sodium cyanide and the bisulfite addition compound. Acrylonittile [107-13-1] (qv) can be made from acetaldehyde and hydrocyanic acid by heating the cyanohydrin that is formed to 600—700°C (77). Alanine [302-72-7] can be prepared by the reaction of an ammonium salt and an alkaU metal cyanide with acetaldehyde this is a general method for the preparation of a-amino acids called the Strecker amino acids synthesis. Grignard reagents add readily to acetaldehyde, the final product being a secondary alcohol. Thioacetaldehyde [2765-04-0] is formed by reaction of acetaldehyde with hydrogen sulfide thioacetaldehyde polymerizes readily to the trimer. 

There are expressions of uncertainty concerning the mechanism of the first step of the Strecker amino acid synthesis13-17. The reaction can proceed via the formation of an imine and subsequent nucleophilic attack of cyanide (path ). Alternatively, it has been speculated that the reaction of the aldehyde with hydrogen cyanide furnishes a cyanohydrin (path ), which then is subjected to a nucleophilic displacement of the hydroxy group by the amino function. 

Answer The Strecker amino acid synthesis (p T 43) requires aldehyde (45) for which a 1,3-diX disconnection is appropriate. 

The Strecker amino acid synthesis, which involves treatment of aldehydes with ammonia and hydrogen cyanide (or equivalents) followed by hydrolysis of the intermediate a-amino nitriles to provide a-amino acids (Scheme 1), was first reported in 1850 [1], This method has been applied on an industrial scale toward the synthesis of racemic a-amino acids, but more recently interest in nonproteinogenic a-amino acids in a variety of scientific disciplines has prompted intense activity in the asymmetric syntheses of a-amino acids [2]. The catalytic asymmetric Strecker-type reaction offers one of the most direct and viable methods for the asymmetric synthesis of a-amino acid derivatives. It is the purpose of this Highlight to disclose recent developments in this emerging field of importance. 

Asymmetric Strecker amino acid synthesis Addition of cyanotrimethylsilane catalyzed by ZnCl2 to optically active aldimines formed from 2,3,4,6-tetrapivaloyl-3-D-galactopyranosylamine as the chiral auxiliary can result in either (R)- or (S)-a-aminonitriles, depending on the solvent. THF or isopropanol favors (R)-dia-stereomers, whereas CHC13 favors the (S)-diastereomers. 

Strecker A (1850) Strecker amino acid synthesis. Liebigs Ann Chem 75 27 5... 

The key synthetic steps in the formation of the desired unnatural amino acids, 5-8, involved the preparation of appropriately substituted cyclobutanones followed by a Btlcherer-Strecker amino acid synthesis.12 The syntheses of the boron-containing amino acids were initiated utlizing alkenes 16 -19. Alkene 17 was prepared by a SN2 displacement of bromide from 4-bromobenzyl bromide (Scheme 3). In the syntheses of alkenes 18 and 19, a catalytic... 

Strecker amino acid synthesis (Section 28.2C) A reaction that converts an aldehyde into an a-amino acid by way of an a-amino nitrile. 

Iyer, M. S., Gigstad, K. M., Namdev, N. D., Lipton, M. Asymmetric catalysis of the Strecker amino acid synthesis by a cyclic dipeptide. Amino Acids 1996, 11, 259-268. 

Strecker amino acid synthesis. Synthesis of a-amino acids by simultaneous reaction of aldehydes with ammonia and hydrogen cyanide followed by hydrolysis of the resulting amino nitriles. 

The preparation of the novel ligand 202b illustrates the general synthetic approach to this class of quaternary a,a-disubstituted glycine sulfonamides (Scheme 17). Menthone (203) is converted to 204 using the Strecker amino acid synthesis procedure. A short sequence of synthetic manipulations subsequently yields the desired amino acid Hgand 206. 

Imines can also be attacked by nucleophiles, such as cyanide, and this is used in the Strecker amino acid synthesis. 

Multicomponent reactions, although fashionable these days, have in fact a long history. Indeed, many important reactions such as the Strecker amino acid synthesis (1850)[6], the Hantsch dihydropyridine synthesis (1882) [7], the Biginelli dihydropyrimidine synthesis (1891)[8], the Mannich reaction (1912) [9], and the isocyanide-based Passerini reactions (1921) (Scheme 5.1) [10], among others, are all... 

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