Improved synthesis of beta-CIT and [11C]beta-CIT labeled at nitrogen or oxygen positions

Nucl Med Biol. 1996 Nov;23(8):981-6. doi: 10.1016/s0969-8051(96)00133-3.

Abstract

The important radiotracer precursor 2 beta-carbomethoxy-3 beta-(4-idophenyl)-tropane (beta-CIT, RTI-55) was made in 52% overall yield from cocaine. Key steps were improved conjugate Grignard addition to anhydroecgonine methyl ester with > 3.5:1 2 beta: 2 alpha-isomer selectivity, and a mild new direct aromatic iodination with I2 and silver triflate in CH2Cl2. The [11C]beta-CIT was labeled at either the N or O positions with [11C]methyl triflate; and efficient reversed-phase HPLC was used to preparatively separate [N-11C]beta-CIT from N-nor-beta-CIT for the first time, and a fast solid-phase extraction (SPE) method was applied to preparatively separate [O-11C]beta-CIT from beta-CIT-acid precursor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Radioisotopes / chemistry*
  • Cocaine / analogs & derivatives*
  • Cocaine / chemical synthesis
  • Isotope Labeling / methods*
  • Mesylates / chemistry
  • Nitrogen / chemistry*
  • Oxygen / chemistry*
  • Radiopharmaceuticals / chemical synthesis*

Substances

  • Carbon Radioisotopes
  • Mesylates
  • Radiopharmaceuticals
  • methyl triflate
  • 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane
  • Cocaine
  • Nitrogen
  • Oxygen