Aromatic nucleophilic substitution of tricarbonylchromium-complexed haloarenes: a new entry to dibenzo crown ethers

Reaction of o-Cl2C6H4Cr(CO)3 with Na[O(CH2)2]2OH in (MeOCH2)2 with Bu4N+ Br- as phase-transfer catalyst at 50° for 8 h followed by decomplexation with iodine gave 27% dibenzo-18-crown-6 (I; X = O) . (OC)3CrC6H4Cl[O(CH2)2]2OH-o and complex II, intermediates in this reaction, were isolated. Reaction of II with NaS(CH2)2O(CH2)2SH gave 15% I (X = S).