Synthesis of Quinolone‐Fused Multi‐Ring‐Sized Heterocycles via Combined Claisen Rearrangement/Ring‐Closing Metathesis Reactions.

Abstract

Abstract: Synthetic strategy on 4-quinolone nucleus couplingaza-Claisen rearrangement and ring-closing metathesis was devel-oped. Thus, quinolone-fused multiring-sized oxygen heterocycles 5a – c were prepared from 5-hydroxy-7-methoxy-3-(4-methoxyphe-nyl)-4(1 H )-quinolone ( 1 ). According to the same strategy, azepi-no[2,3- f ]quinolone derivative 9 was synthesised from triflate 6 . Key words: quinolone, Claisen rearrangement, olefin, ring-closingmetathesis The ring-closing metathesis (RCM) reaction has becomea versatile method for constructing cyclic alkenes oralkynes. 1 This method has rapidly evolved into a routinetool for the synthesis of natural products, 2 medium-ringand macro-ring carbocyclic or heterocyclic motifs. 3 Thegeneralisation into synthetic organic chemistry has beendriven primarily by the discovery of well-defined andfunctional-group-tolerant catalysts independently bySchrock and Grubbs. 1e In our ongoing research of new 4-quinolones with poten-tial antitumor activity,