Compound 3a

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InChIKey PZQMNYZWXCXNMU-SXUBXDNWSA-M

Compound data: CIF

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

A solution of HBF₄·H₂O (85 μL, 0.50 mmol) was added to a solution of compound 2a (300 mg, 0.25 mmol) in dichloromethane (15 mL). After stirring at room temperature for three hours, the resulting reddish-brown solution was evaporated under vacuum to a ca. 2 mL volumn; diethyl ether (20 mL) was then added. The yellow precipitate was collected by filtration, washed with diethyl ether (2 × 5 mL), and dried under vacuum to give 3a (227 mg, 73%) as a yellow solid. ¹H-NMR plus ¹H-¹³C HSQC (500.1 MHz, CDCl₃): δ 13.30 (d, J_P-H = 17.3 Hz, 1H, H¹), 8.99 (s, 1H, H³), 8.09 (s, 1H, H⁵), 3.57 (s, 3H, COOCH₃), 7.88–6.94 ppm (m, 45H, other aromatic protons). ³¹P-NMR (202.5 MHz, CDCl₃): δ 13.63 (t, J_P-P = 4.9 Hz, CPPh₃), 5.60 ppm (d, J_P-P = 4.9 Hz, OsPPh₃). ¹³C-NMR plus DEPT-135 and ¹H-¹³C HSQC (125.8 MHz, CD₂Cl₂): δ 330.8 (td, J_P-C = 15.5 Hz, J_P-C = 6.1 Hz, C⁷), 224.2 (br, C¹), 180.3 (d, J_P-C = 18.5 Hz, C⁴), 162.0 (s, C⁵), 159.9 (s, COOCH₃, confirmed by ¹H-¹³C HMBC), 152.8 (s, C⁶), 147.8 (d, J_P-C = 21.1 Hz, C³), 118.8 (d, J_P-C = 88.7 Hz, C²), 51.6 (s, COOCH₃), 135.3–127.8 ppm (m, other aromatic carbons). HRMS (ESI): m/z calcd for [C₆₃H₅₁ClO₂OsP₃]⁺, 1159.2394; found, 1159.2416.