The present invention is a compound of formula IB ^{[Formula, A 1, A 2, A} 3, A 4, L, Y 1, Y 2, R 1, R 2, R 3, R 4, and R ⁵ in claim method for producing a compound represented by the following in which] are defined. This method is a compound of formula II ^{[Formula, Y 1, Y 2, L} , A 1, A 2, R 1, R 2, R 3, R 4, and R ^5, the compound represented by the formula I the compound represented by are as defined], water, base and in the presence of a chiral phase transfer catalyst, comprising reacting with hydroxylamine, the chiral phase transfer catalyst is a quinine derivative. Invention also relates to enantiomerically enriched mixtures compounds of formula IB and comprising a compound of formula IB.