Epoxide ring opening in a zinc(II) complex in water without any Lewis acid catalyst: Formation of only one diastereomer out of 23

The epoxide ring in 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) opens up in its reaction with 4-methylaniline and 4-methoxyaniline in water in equimolar proportion at room temperature without any Lewis acid catalyst to give a monohydrate of 6-(4-methyl-phenylamino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L'center dot H2O) and 6-(4-methoxyphenyl-amino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L '') respectively. Reaction time decreases from 72 to 14 h in boiling water. But the yields become less. Reaction of L with Zn(ClO4)(2)center dot 6H(2)O in methanol in 3:1 molar ratio at room temperature affords white [ZnL3](ClO4)(2)center dot H2O. The X-ray crystal structure of the acetonitrile solvate [ZnL3](ClO4)(2)center dot MeCN has been determined which shows that the metal has a distorted octahedral N-6 coordination sphere. [ZnL3](ClO4)(2)center dot 2H(2)O reacts with 4-methylaniline and 4-methoxyaniline in boiling water in 1:3 molar proportion in the absence of any Lewis acid catalyst to produce [ZnL3'](ClO4)(2)center dot 4H(2)O and [ZnL3 ''](ClO4)(2)center dot H2O, respectively in 1-4 h time in somewhat low yield. In the H-1 NMR spectra of [ZnL3'](ClO4)(2)center dot 4H(2)O and [ZnL3 ''](ClO4)(2)center dot H2O, only one sharp methyl signal is observed implicating that only one diastereomer out of the 2(3) possibilities is formed. The same diastereomers are obtained when L'center dot H2O and L '' are reacted directly with Zn(ClO4)(2)center dot 6H(2)O in tetrahydrofuran at room temperature in very good yields. Reactions of L'center dot H2O and L '' with Ru(phen)(2)Cl-2 center dot 2H(2)O (phen = 1,10-phenanthroline) in equimolar proportion in methanol-water mixture under refluxing condition lead to the isolation of two diastereomers of [Ru(phen)(2)L'](ClO4)(2)center dot 2H(2)O and [Ru(phen)(2)L ''](ClO4)(2)center dot 2H(2)O. (C) 2011 Elsevier B.V. All rights reserved.