Triethylamine carboxy group

Protection and Deprotection.— The formation of esters of 2-hydroxymethyl-anthraquinone has been shown to be a useful method for the protection of carboxy-groups of a-amino-acids. Such derivatives, designated Maq esters, are stable to TEA, HCl, and triethylamine, and can be hydrolysed in quantitative yield by a number of methods. They offer, moreover, the advantages of high crystallinity and... 

Treatment of 3-acylaminoperhydropyrido[2,l- >][1,3]thiazine-6-carboxy-late (109) with iodotrimethylsilane gave a 3-amino derivative (110). The amino group was acylated with (5)-2-(acetylthio)-3-phenylpropionic acid in the presence of benzotriazol-l-yloxitris(dimethylamino)phosphonium hexafluorophosphate and triethylamine in dichloromethane, and the product (111) was hydrolyzed to 112 (94EUP629627 96USP5508272). 

Ring closure of (3-hydroxy-a-amino acids with sulfuryl chloride/triethylamine 68 is accompanied by formation of (3-chloroalanine,16 1 whereas cyclization of urethane-protected serine and threonine by the Mitsunobu reaction 54 69 70 leads to oxazoline and dehydroalanine formation as side products. 47,71 Formation of dehydroalanine can be prevented by bulky carboxy protecting groups such as tert-butyl esters. 69 ... 

The secondary amino group of 3-(Al-ethylaminomethyl)-7-[2-(2-amino-thiazol-4-yl)-2-(Z-1 -carboxy-1 -methylethoxyimino)acetamido]ceph-3-em-3-carboxylic acid was arylated with 8-methylthiopyrido[l,2-a]pyrimidi-nium salt in dimethylformamide in the presence of triethylamine at 40°C (89MIP2). 

Diacetyl-3,6-dibenzylpiperazine-2,5-dione (15) reacted with sulfur in dimethyl-formamide and triethylamine to form, after hydrolytic removal of the acetyl groups, 3-benzyl-6-benzylidenepiperazine-2,5-dione (16) (1068). 2-Chloro-5-hydroxy-3,6-dimethylpyrazine heated with solid potassium hydroxide gave 3-hydroxy-2,5-dimethylpyrazine (312), and 2-chloro-6-hydroxy-3,5-diphenylpyrazine with an excess of methanolic sodium methoxide at 150° formed 2-hydroxy-3,5-diphenylpyrazine (873). Decarboxylation of 2-carboxy-3-hydroxypyrazine gave 2-hydroxypyrazine (420) and in this way 24iydroxy[2- C]pyrazine (823) and 2-hydroxy[l- N]pyrazine (822) have been prepared. 

More recently Rathke and coworkers have described a procedure involving the carboxylation of a ketone in the presence of magnesium halide and triethylamine in acetonitrile with an optimal ratio of amine halide ketone of 4 2 1. Advantages included a lower reaction temperature and a solvent more readily removed (equation 40). The reaction showed little regioselectivity, as 2-butanone was carboxy-lated on the methyl and methylene groups in a ratio of SS 4S. The same group reacted a magnesium enol-ate with butenone in the initial Michael step of a Robinson annelation. 

A more recent synthesis by our group utilized Mukaiyama s trimethylsilyl cyanide addition to aldehydes as the key step to introduce the carboxy functionality [33,36], This approach also required the preparation of (Z)-5-pentadecenal as the key intermediate, Fig. (12). In this case, commercially available decyl aldehyde was coupled with 4-carboxybutyltriphenylphosphonium bromide under Wittig conditions, resulting in a 10 1 mixture of the known (Z)- and ( )-5-pentadecenoic acids. The acids were then reduced to the desired (Z)-5-pentadecenal via (Z)-5-pentadecen-l-ol, a known pheromone. Addition of trimethylsilyl cyanide to (Z)-5-pentadecenal, under triethylamine catalysis, yielded... 

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