UNSPECIFIED (2004) Synthetic 6-aryl-2-hydroxy-6-ketohexa-2,4-dienoic acid substrates for C-C hydrolase BphD: investigation of a general base catalytic mechanism. ORGANIC & BIOMOLECULAR CHEMISTRY, 2 (20). pp. 2942-2950. doi:10.1039/b410322j

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Abstract

A chemical synthesis of the 2-hydroxy-6-ketohexa-2,4-dienoic acid intermediates on bacterial meta-cleavage pathways has been established, using a Heck coupling strategy. Coupling of ethyl 3-bromo-2-acetoxyacrylate with 1-aryl vinyl ketals or 1-aryl allylic alcohols proceeded in 70-90% yield. Heck coupling with an alkyl vinyl ketal was also successful, allowing the synthesis of an alkyl-substituted ring fission intermediate. The synthetic ring fission intermediates were used to investigate the enzymatic reaction catalysed by C-C hydrolase BphD from Pseudomonas LB400. A reduced substrate analogue 2,6-dihydroxy-6-phenylhexa-2,4-dienoic acid was processed enzymatically to benzaldehyde by C-C hydrolase BphD, consistent with a catalytic mechanism involving general base-catalysed attack of water to give a gem-diol intermediate, and not consistent with a nucleophilic mechanism. A series of para-substituted 2-hydroxy-6-keto-6-phenylhexa-2,4-dienoic acid substrates were assayed against BphD, and the derived Hammett plot (rho=-0.71) is consistent with a departing carbanion in the transition state for C-C cleavage.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Journal or Publication Title:	ORGANIC & BIOMOLECULAR CHEMISTRY
Publisher:	ROYAL SOC CHEMISTRY
ISSN:	1477-0520
Official Date:	2004
Dates:	Date Event 2004 UNSPECIFIED
Volume:	2
Number:	20
Number of Pages:	9
Page Range:	pp. 2942-2950
DOI:	10.1039/b410322j
Publication Status:	Published

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