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Updated: Aug 20, 2026

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products
Published on: September 9, 2016
No-carrier-added synthesis of a 4-methyl-substituted meta-iodobenzylguanidine analogue
G Vaidyanathan1, D J Affleck, M R Zalutsky
1Department of Radiology, Duke University Medical Center, Box 3808 Radiology, Bryan Research Building, Durham, NC 27710, USA. ganesan.v@duke.edu
Abstract:
Radioiodinated meta-iodobenzylguanidine (MIBG) is used in the diagnosis and therapy of various neuroendocrine tumors. As a part of our efforts to develop an MIBG analogue with improved characteristics for these applications, a synthesis of 3-[131I]iodo-4-methylbenzylguanidine ([131I]MeIBG) was developed. Unlabeled MeIBG and the tin precursor, N, N'-(bis-tert-butyloxycarbonyl)-N-(4-methyl-3-trimethylstannylbenzyl) guanidine were synthesized in two steps from 3-iodo-4-methylbenzylalcohol. Radioiodinated MeIBG was synthesized at a no-carrier-added level by the iododestannylation of the tin precursor in about 85% radiochemical yield. The accumulation of [131I]MeIBG (38.9+/-3.0% of input counts) by human neuroblastoma SK-N-SH cells in vitro was 87% that of [125I]MIBG (44.5+/-3.0%) and a number of Uptake-1 inhibiting conditions reduced the uptake of both tracers in this cell line to a similar degree suggesting that introduction of a methyl substituent at the 4-position of MIBG did not adversely affect its biological characteristics.
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