ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
(±)-Norcoclaurine-1-carboxylic acid (5) and the derived dihydroisoquinolinone 6 (present as quinonemethide 6a at pH 7) afforded, on methylation with 14C-labeled S-adenosyl-L-methionine in the presence of mammalian catechol O-methyltransferase, exclusively the 7-O-methylated congeners 7 and 9, respectively. High stereoselectivity of the O-methylation was observed with (-)-(S)- and (+)-(R)-norcoclaurine (2a and 2b, resp.), affording 80% of 6-O-methylated isoquinoline 12 and 20% of the 7-O-methylated isomer 11 from 2a, and the reversed proportion of 12 and 11 from 2b. Synthesis of the reference amino acid 8 was achieved by Pictet-Spengler condensation of O-benzyl-protected dopamine 17 with benzyl-protected keto acid 20 (→ 21) followed by methylation with diazomethane (→22 + 23) and removal of the protecting groups by acid hydrolysis. It is considered unlikely that amino acids such as 5 constitute important precursors in the biosynthesis of isoquinolines related to reticuline.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19900730222
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