Table 3.

Epoxidation with diastereomeric sulfonium salts under nonreversible conditions

Entry	Conditions	Yield, %*	Trans/cis†	ee %‡
1	21, KOH, CH3CN/H2O (9:1), rt	75	98:2	98 (R,R)
2	22, KOH, CH3CN/H2O (9:1), rt	83	91:9	95 (S,S)
3	22, EtP2, CH2Cl2, -78 °C§	100	>98:2	98.5 (S, S)

^*Yield of isolated material.

^†Determined by ¹H NMR of crude reaction mixture.

^‡Determine by chiral HPLC on Chiracel OD column.

^§EtP₂ = N,N,N′,N′-tetramethyl-N″ -(tris(dimethylamino)phosphoranylidene)-phosphoric triamide ethylimine.