Convergent and short-step syntheses of dl-Cypridina luciferin and its analogues based on Pd-mediated cross couplings

dl-Cypridina luciferin and its analogues were synthesized from 2-aminopyraz ine by an eight-step method that included two regio-selective Pd-mediated c ross couplings, and their chemi- and bioluminescent activities were compare d. Analogues having a 3-benzofuranyl or a 3-benzothienyl group in the place of a 3-indolyl group showed luciferase affinities similar to Cypridina luc iferase but with a lower luminescent efficiency, suggesting that the NH gro up is unimportant for molecular recognition whereas the indolyl group is cr ucial for efficient luminescence. (C) 2000 Elsevier Science Ltd. All rights reserved.