Synthesis of isomeric 1,4-[C-13](2)-labeled 2-ethoxycarbonyl-1,4-diphenylbutadienes

The 1,4-bis-C-13-labeled isomeric compounds (Z,E)- and (E,E)-2-ethoxycarbon yl-1,4-diphenylbutadiene have been synthesized by two different methods. A double Horner-Wadsworth-Emmons (HWE) strategy was employed for the synthesi s of the Z,E isomer. On the other hand, synthesis of the E,E isomer was ach ieved by Baylis-Hillman reaction of benzaldehyde with ethyl acrylate and su bsequent rearrangement, followed by Wittig olefination with benzaldehyde. T hese routes provide stereoselective access to labeled compounds in good yie lds. (C) 2001 Elsevier Science Ltd. All rights reserved.