Reaction SMILES: C[C@]1(CSC2C=CC=CC=2)[C@H]2C[C@H]([C@](C)(O)CC2)OO1.C[C@@]1(CSC2C=CC=CC=2)[C@H]2C[C@H]([C@](C)(O)CC2)OO1.N1C=CC=CC=1.C(Cl)(C)=O.[C:51]([O:54][C@@:55]1([CH3:73])[C@H:62]2[CH2:63][C@H:58]([C@:59]([CH3:72])([CH2:64][S:65][C:66]3[CH:71]=[CH:70][CH:69]=[CH:68][CH:67]=3)[O:60][O:61]2)[CH2:57][CH2:56]1)(=[O:53])[CH3:52]>CN(C1C=CN=CC=1)C.C(Cl)Cl.CCCCCC.CCOC(C)=O.O>[C:51]([O:54][C@@:55]1([CH3:73])[C@H:62]2[CH2:63][C@H:58]([C@@:59]([CH3:72])([CH2:64][S:65][C:66]3[CH:71]=[CH:70][CH:69]=[CH:68][CH:67]=3)[O:60][O:61]2)[CH2:57][CH2:56]1)(=[O:53])[CH3:52]
Reactant: CC(=O)O[C@]1(C)CC[C@@H]2C[C@H]1OO[C@@]2(C)CSc1ccccc1
Agent: CN(C)c1ccncc1
Agent: C[C@@]1(O)CC[C@@H]2C[C@H]1OO[C@@]2(C)CSc1ccccc1
Agent: C[C@]1(CSc2ccccc2)OO[C@@H]2C[C@H]1CC[C@@]2(C)O
Solvent: CCOC(C)=O
Solvent: c1ccncc1
Solvent: O
Product: CC(=O)O[C@]1(C)CC[C@@H]2C[C@H]1OO[C@]2(C)CSc1ccccc1
Temperature: 0 °C
Reaction time: 12 h
Yield: 52.9 %

Procedure:
To a solution of sulfides 2a and 2b (1.15 g, 3.91 mmol, 2a/2b 55:45), pyridine (1.54 g, 19.5 mmol) and DMAP (49 mg, 0.4 mmol) in dry CH2Cl2 (30 mL) at 0° C. was added a solution of AcCl (1.22 g, 15.6 mmol) in CH2Cl2 (5 mL). The mixture was stirred for 1 h at 0° C. and for 12 h at rt The dark reaction mixture was poured into water (100 mL), extracted with hexane-EtOAc (7:3 mixture, 3×100 mL), dried (Na2SO4 +NaHCO3) and evaporated. The residue was separated by flash chromatography (gradient elution, hexane-EtOAc, 9:1→7:3) to give: (i) unreacted hydroxysulfides 2a and 2b (292 mg, 0.99 mmol, 25.4%); (ii) a mixture of diastereomers (1R,4R,5R,8R)-8-acetoxy-4,8-dimethyl-4-phenylthiomethyl-2,3-dioxabicylo[3.3.1]nonane 13a and (1R,4S,5R,8R)-8-acetoxy-4,8-dimethyl-4-phenylthiomethyl-2,3-dioxabicyclo[3.3.1]nonane 13b (518 mg, 1.54 mmol, 52.9% yield, 13a/13b ca. 55:45) as a colorless viscous liquid, Rf 0.67 (hexane-EtOAc 7:3); (iii) a mixture of diastereomers (1R,4R,5R8R)-8-acetylacetoxy-4,8-dimethyl-4-phenylthiomethyl-2,3-dioxabicyclo[3.3.1]nonane 14a and (1R,4S,5R,8R)-8-acetylacetoxy-4,8-dimethyl-4-phenylthiomethyl-2,3-dioxabicyclo [3.3.1]nonane 14b (152 mg, 12.6% yield, 14a/14b ca. 54:46; keto/enol ca. 91:9) as a colorless oil, Rf 0.40 (hexane-EtOAc 7:3); (iv) a mixture of diastereomers of E-enolacetates E-15a,b (48 mg, 0.105 mmol, 3.6% yield, E-15a/E-15b ca. 54:46) as a yellowish viscous oil, Rf 0.61 (hexane-EtOAc 7:3); (v) a mixture of diastereomers of Z-enolacetates Z-15a,b (41 mg, 0.090 mmol, 3.1% yield, Z-15a/Z-15b ca. 52:48) as a yellowish viscous oil, Rf 0.50 (hexane-EtOAc 7:3). Spectral data for 13a,b: IR (neat); 692, 742, 1022 v.s, 1054, 1204, 1223, 1254 v.s, 1371 v.s, 1453, 1732 v.s, 2935 cm-1. 1H NMR (CDCl3, 400 MHz) (δ): 1.24 (br.s, Me11, 13a), 1.56 (br.s, Me11, 13b), total 3H; 1.65 (s, Me10, 13b), 1.66 (s, Me10, 13a), total 3H; 1.67-1.89 (m, 3H, He6 +Ha6 +Ha9, 13a+13b); 1.74 (m, He5, 13b), 1.90 (dddd, 3J5e6e =3J5e9e =6.6 Hz, 3J5e6a =3J5e9a =3.3 Hz, He5, 13a), total 1H; 2.07 (ddd, 2J9e9a =14.1 Hz, 3J9e5e =6.6 Hz, 3J9e1e =3.4 Hz, He9,13a), 2.27 (m, He9, 13b), total 1H, 2.12-2.20 (m, 1H, He7, 13a+13b); 2.25 (ddd, 2J7a7e =15.0 Hz, J7a6a =13.2 Hz, 3J7a6e =6.0 Hz, Ha7, 13b), 2.28 (ddd, 2J7a7e =14.3 Hz, J7a6a =13.3 Hz, 3J7a6e =6.0 Hz, Ha7, 13a), total 1H; 2.95 (H12,13b)) and 3.02 (4J12,11 =0.4 Hz, H'12,13b), (ABq, 2J=12.0 Hz), 3.30 (d,2J=12.8 Hz, H12,13a) and 3.72 (dd, 2J=12.8 Hz, 4J12,11 =0.5 Hz, H12,13a), total 2H;4.40 (dd, 3J1e9e =3.4 Hz, 3J1e9a =1.0 Hz, H1,13a), 4.44 (dd, 3J1e9e =3.4 Hz, 3J1e9a =0.8 Hz, H1, 13B), total 1H; 7.17-7.23 (m, 1H, H16,13a+13b); 7.29 (m, 2H, H15, 13a+13b); 7.37 (m, 2H, H14, 13a+13b). 13C NMR (CDCl3, 100 MHz) (δ): Isomer 13a: 22.03 (Me11), 22.42 (Me10), 22.55 (Me17C=O), 23.50 (C6H2), 23.97 (C9H2), 28.52 (C5H), 32.88 (C7H2), 40.71 (C12H2), 77.46 (C1H), 82.76 (C8), 83.85 (C4), 126.24 (C16H), 128.91 (2C14H), 129.76 (2C15H), 136.73 (C13), 170.13 (C=O); Isomer 13b: 21.77 (Me11),22.53 (Me10), 22.55 (Me17C=O) 23.22 (C6H2), 24.09 (C9H2), 29.89(C5H), 33.20 (C7H2), 40.81 (C12H2), 77.91 (C1H), 82.67 (C8), 83.73 (C4), 126.43 (C16H), 128.96 (2C14H), 129.73 (2C15H), 136.29 (C13), 170.13 (C=O). Spectral data for 14a,b: 1H NMR (CDCl3, 400 MHz) (δ): 1.23 (br.s, Me11, 14a), 1.55 (br.s, Me11,14b), total 3H; 1.68 (s, Me10,14b), 1.69 (s,Me10,14a), total 3H; 1.70-1.93 (m, 4H); 2.08 (ddd, 2J9e9a =14.0 Hz, 3J9e5e =6.5 Hz, 3J9e1e =3.5 Hz, He9, 14), 2.15-2.33 (m), total 3H; 2.25 (s, Me18C=O, 14a), 2.26 (s,Me18C=O,14b), total 3H;2.95 (H12,14b) and 3.00 (br.,H'12, 14b), (ABq, 2J=12.6 Hz),3.31 (d, 2J=12.8 Hz, H12,14a) and 3.69 (br.d, 2J=12.8 Hz, H12, 14a), total 2H;3.40 (s, C17H2C=O, 14a), 3.41 (s, C17H2C=O, 14b), total 2H; 4.37 (br.d, 3J1e9e =3.5 Hz, He1, 14aketo), 4.41 (br.d, 3J1e9e =3.6 Hz, He1,14bketo), 4.45 (br.d, 3J1e9e =3.5 Hz, He1, 14aenol), 4.49 (br.d, 3J1e9e =3.5 Hz, He1, 14benol), total 1H; 4.92 (br.s, HC=, 14aenol), 4.94 (br.s, HC=,14benol); 7.26-7.42 (m, 5Harom., 14a+14b); 1.205 (br.s, HOenol, 14a+14b). 13C NMR (CDCl3, 100 MHz) (δ): Isomer 14a: 21.89 (Me11), 22.48 (Me10), 23.28 (C6H2), 23.74 (C9H2), 28.43 (C5H), 30.15 (Me18C=O),32.67 (C7H2), 40.59 (C12H2),51.18 (C17H2), 77.30 (C1H), 83.76 (C4), 84.25 (C8), 90.60 (HC17 =enol), 126.16 (16H), 128.83 (2C14H), 129.65 (2C15H), 136.62 (C13), 165.83 (OC20 =O), 200.57 (C19 =O); Isomer 14b: 21.64 (Me11),22.49 (Me10), 22.98 (C6H2), 23.85 (C9H2), 29.74 (C5H), 30.15 (Me18C=O), 33.02 (C7H2), 40.75 (C12H2), 51.18 (C17H2), 77.72 (C1H), 83.82 (C4), 84.17 (C8), 90.60 (HC17 =enol), 126.37 (C16H), 128.88 (2C14H), 129.68 (2C15H), 136.18 (C13), 165.84 (OC20 =O), 200.57 (C19 =O).