Table 3. Kinetic Resolution of Olefins Using Asymmetric Epoxidation Mediated Using Catalyst 3^a.

starting material	conv. (%)b	epoxide	epoxide d.r. (trans:cis)d	major epoxide trans-diastereoisomer ee (%)c	minor epoxide cis-diastereoisomer ee (%)c	recovered chromene ee (%)c	krele
13a	48	(−)-17a	2.5:1	87	97	26	2.3
13b	52	(−)-17b	3:1	86	97	37	2.9
14a	50	(−)-18a	4:1	87	98	40	3.4
14b	56	(−)-18b	3.5:1	73	92	41	2.8
15a	26	(+)-19a	trans only	76		17	3.4
15b	37	(+)-19b	trans only	74		14	1.9
16a	38	(−)-20a	10:1	76	82	42	8.0
16b	36	(−)-20b	16:1	88	99	50	27.9

^aAll reactions were carried out with substrate (1 equiv), catalyst (10 mol %), and tetraphenylphosphonium monoperoxysulfate (TPPP) (4 equiv) in CHCl₃ at −30 °C.

^bConversion was determined from the ¹H NMR spectra of the crude reaction mixture.

^cEnantioselectivity was determined using chiral stationary phase HPLC with a Chiralcel OD-H column.

^dDiastereoisomeric ratios were determined from the ¹H NMR spectra of the reaction mixture after workup.

^ek_rel = ln[(l – C)(1 – ee)]/ln[(l – C)(1 + ee)], where C is the fraction of 13, 14, 15, or 16 consumed and ee is the percentage enantiomeric excess/100.^21,22,36