Regio- and diastereoselective formation of some (eta(6)-2-methylindoline)tricarbonylchromium(0) complex derivatives

Complexation of 2-methylindoline 1 and its derivatives 2 and 3 with Cr(CO)( 6) gave complexes 4-9. With the TIPS group attached to the nitrogen atom as in compound 3, the complexation was completely diastereoselective producin g the endo complex 9. Treatment of the metallated complexes 8 and 9 with 2- halobenzoyl chlorides as electrophiles allowed for totally regioselective f unctionalisation at C(4), while the exo complex 6 was functionalised both a t C(4) and C(7); with TMSCl and TIPSCl as electrophiles, the endo complex 9 also exhibited minor exo benzylic substitution to give 25 and 27. Oxidativ e decomplexation of the indoline complexes efficiently releases the free 4- substituted indolines. (C) 2001 Elsevier Science B.V. All rights reserved.