Optimisation of the enantioselective oxygenation of 3-(4′-methylbenzyl)-quinolone (2a) catalysed by the chiral manganese porphyrin complex 1 (DCE = 1,2-dichloroethane).

Entrya	c b [mM]	1 [mol%]	Solvent	3a c [%]	% eed	4a c [%]
1	30	1.0	CH2Cl2	48	91	11
2e	20	1.0	CH2Cl2	42	93	13
3	20	1.0	CH2Cl2	39	86	11
4	60	1.0	CH2Cl2	50	87	12
5	30	2.0	CH2Cl2	48	91	10
6f	30	1.0	PhH	30	85	3
7	30	1.0	DCE	42	88	12
8g	30	1.0	CH2Cl2	45	85	12
9h	30	1.0	CH2Cl2	52	93	17
10h	30	0.5	CH2Cl2	37	—i	10
11h	30	1.5	CH2Cl2	56	95	18

^aAll reactions were run with 3.0 equiv. of 2a (180 μmol) under the indicated conditions (0 °C, t = 4 h) and were initiated by addition of the oxidant PhIO (1.0 equiv.) to a pre-cooled solution of 2a and 1 in the given solvent.

^bConcentration of quinolone 2a in the solution.

^cAll yields were determined by GLC-FID analysis using ⁿdodecane as a stoichiometric internal standard.

^dEnantiomeric excess (% ee) as determined by HPLC analysis on a chiral stationary phase.

^e2.0 equiv. of 2a were employed.

^fThe reaction was performed at 23 °C.

^gThe reaction time was 16 h.

^hPhIO was added in three portions.

ⁱNot determined.