Efficient highly stereoselective synthesis of olefinic macrocyclic crown-formazans with the Z-configuration via ring-closure metathesis

Formazans and their metal complexes

“…26 The introduction of podands containing oligooxyethylene bridges of various lengths between two formazan fragments afforded new classes of bisverdazyls (23) and bisverdazylium salts (24) (Scheme 3). 27 Bisverdazyls 23 represent a novel class of stable biradicals: solid samples decompose at room temperature only after several days, while their solutions in organic solvents do not change optical densities over a course of several weeks.…”

New trends in the chemistry of condensed heteromacrocycles part B: Macrocyclic formazans

“…The reaction proceeds to give "1+1" macrocyclic and/or "2+2" macrocycles [31,36]. Cyclizations are possible using functional groups at each end where the formazyl groups are in the center of the starting bis-functional materials (Scheme 7,8) [37,38].…”

“…In the last decade RCM and its wide range of applications have been the subject of many reviews [46]. Very recently, Ibrahim et al [38] reported the synthesis of some crown formazan derivatives 61a-g using ring closure metathesis with Grubb's Catalyst as the key macrocyclization step as outlined in Scheme 19.…”

The chemistry of the carbon–transition metal double and triple bond: annual survey covering the year 2002

“…119) [370][371][372][373][374][375][376][377][378][379][380]; (6) formation of macrocyclic diazacyclic-diethers (e.g. 120) [381][382][383]; (7) formation of macrocyclic lactone-acylamides [384]; (8) formation of macrocyclic carbocyclic rings fused to ␥-lactones (e.g. 121) and the effect of lactone stereochemistry on the macrocyclic RCM [385]; (9) synthesis of macrocyclic diesters of 3,5-pyridinedicarboxylic acid (e.g.…”