Olfactory recognition of a trimethylsilylcarbamate as a carboxylic acid

Autor: D. C. Jewett
Rok vydání: 1992
Předmět:
Zdroj: Die Naturwissenschaften. 79(11)
ISSN: 0028-1042
Popis: This reaction has been implicated in the normal function of hemoglobin [2] and possibly of tubulin [3]. A strong case has recently been made that N-carboxylation is involved in the excitatory neurotoxicity of cysteine [4] and/3-Nmethylamino-L-alanine [5]. The NMDA receptor may recognize the carbamate moiety of N-carboxycysteine as equivalent to the -CHzCOOside chain of N-methyl-D-aspartate. In addition to degenerative neurotoxicity, such a mechanism may also contribute to reversible CO 2 intoxication [6] by causing simultaneous, transient changes in the structure of a number of chemical species in the brain. The implication of reversible N-carboxylation as broadly relevant to neuropathology recalls the accidental discovery of another case in which a cellular receptor appears to recognize a carbamate group as a carboxylic acid. Carbon dioxide inserts into the Si-N bond of silylamino groups to form silylcarbamates [7] : the characteristic odor for some time. Apparently the silylcarbamate hydrolyzed in contact with the olfactory epithelium to give the free carbamic acid or anion, an isostere of the powerful odorant, cyclohexane carboxylic acid. The piperidinium salt of the anion 3 lacked the fatty acid odor. The trimethylsilyl group apparently allowed the carbamate to have sufficient volatility and lipophilicity to reach the receptor site. Because of the lability of the -C(O)OSi(CH3) 3 group toward atmospheric moisture the more hindered triethylsilyl analog was synthesized. While the fatty acid odor was recognizable and more persistent, the effect was complicated by the camphoraceous odor contributed by the bulky triethylsilyl
Databáze: OpenAIRE
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