Bromoethene → α-Ethenyl-3,4-dihydro-α,4,4-trimethyl-2H-1-benzothiopyran-6-methanol

Participants

Reaction Steps

To a freshly prepared solution of vinylmagnesium bromide; [7.65 g (0.0715 mol) of vinyl bromide and 1.75 grams (0.0720 g at) of magnesium in 40 mL of dry THF], 10.5 g (0.0477 mol) 6-acetyl-4,4-dimethylthiochroman in 25 mL of THF was added dropwise under N2 in a 200-mL, round-bottom flask equipped with a condenser and nitrogen inlet. The solution was then boiled for 1 hour and allowed to stir for 10 hours at room temperature. Saturated NH4Cl was added in 1-mL portions until the solution was slightly acidic (pH approx. 6.8 ), and 100 mL of ether was added and the two layers separated. The aqueous layer was extracted with ether (4×100 mL) and the ether extracts were combined with the original organic layer. The combined organics were washed with 50 ml of H2O and 50 mL of brine and was then dried (Na2SO4, 4 h). After evaporation, the resulting oil was used without further purification; IR (neat) 3200-3600 cm-1 (OH); 1H (DCCl3) δ1.32 [s, 6 H, (CH3)2C], 1.95 [m, 2 H, ArSCH2CH2 ], 2.11 [bs, 1 H, OH], 3.00 [m, 2 H, ArSCH2CH2 ], 5.14 [dd, 1 H, J=2.0 Hz, J=10.5 Hz, CH=CH2 (cis)], 5.30 [dd, 1 H, J=2.0 Hz, J=15.0 Hz, CH=CH2 (trans)], 6.16 [dd, 1 H, J=10.5 Hz, J=15.0 Hz, CH=CH2 ], 7.05 [d, 1 H, J=8 Hz, H(8)], 7.12 [dd, 1 H, J=Hz, J=8 Hz, H(7)], 7.52 [d, 1 H, J= 2 Hz, H(8)]; 13C (DCCl3) ppm 22.9 [ArSSCH2CH2 ], 29.1 [CH3COH], 30.2 [(CH3)2C], 33.1 [(CH3)2C], 37.3 [ArSCH2CH2 ], 74.5 [CH3COH], 112.1, 123.2, 126.2, 130.2, 141.6, 142, 144.7. ##STR15##

Provenance & Evidence