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2nd August 2010 @ 09:14
Intermediate for the preparation of 1,1-Binaphthyl-2,2-disulfonate – a strong achiral Brønstedt-acid, intended for determination and optimization of the reaction conditions for the acid-catalyzed Pictet-Spengler reaction [1,2]


Hazard and Risk Assessment:
Reaction Class: 2
Hazards: T toxic, X Irritant, C Corrosive, F Flammable
Risk rating: U = Unlikely

Start time: 4:30 AM 02/08/2010
End time:

Procedure: [1]
To an ice cooled solution of (+/-)-1,1’-bi(2-naphthol) (1.00g, 3.49 mmol) in dry DMF (10 mL) under argon was added sodium hydride (350 mg, 8.73 mmol, 2.5 eq.; 60% oil dispersion), warmed to room temperature and stirred for 10 min. The resulting yellow solid was slightly heated to obtain a yellow dispersion. To the dispersion N,N-dimethylthiocarbamoyl chloride (950 mg, 7.68 mmol, 2.2 eq.) was added at room temperature and heated to 85°C for XX h.

References:
[1] “Pyridinium 1,1′-Binaphthyl-2,2′-disulfonates as Highly Effective Chiral Brønsted Acid−Base Combined Salt Catalysts for Enantioselective Mannich-Type Reaction”, M. Hatano, T. Maki, K. Moriyama, M. Arinobe and K. Ishihara, J. Am. Chem. Soc. 2008, 130, 16858–16860; DOI: 10.1021/ja806875c.

[2] “A Powerful Chiral Counteranion Motif for Asymmetric Catalysis”, P. García-García, F. Lay, P. García-García, C. Rabalakos, B. List, Angew. Chem. Int. Ed. 2009, 48, 4363 –4366; DOI: 10.1002/anie.200901768.

Procedure from the reference:
(R)-1,1’-Binaphthalene-2,2’-diyl-O,O’-bis(N,N-dimethylthiocarbamate)
(3):1,2 An ice cooled solution of (R)-BINOL (14.3 g, 50.0 mmol) in 100 mL of distilled DMF
under N2 was treated under vigorously stirring with NaH (4.4 g, 110 mmol; 60% oil dispersion).
To the resulting yellow solution was added N,N-dimethylthiocarbamoyl chloride (13.6 g, 110
mmol) at 0 °C, and the solution was warmed at 85 °C for 1 h by monitoring with the TLC. Then,
the reaction mixture was cooled to room temperature and poured into 1% aqueous KOH (300 mL).
The colorless precipitate was filtered, washed thoroughly with water, and dissolved in CH2Cl2.
The CH2Cl2 solution was dried over MgSO4 and evaporated to obtain a colorless solid that was
recrystallized from CHCl3/hexane (20.2 g, 88% yield). 1H NMR (300 MHz, CDCl3) δ 2.52 (s,
6H), 3.08 (s, 6H), 7.30 (ddd, J = 8.4, 7.1, 0.9 Hz, 2H), 7.42-7.48 (m, 4H), 7.62 (d, J = 8.7 Hz, 2H),
7.91 (d, J = 8.7 Hz, 2H), 7.97 (d, J = 8.7 Hz, 2H). 13C NMR (75 MHz, CDCl3) δ 37.9 (2C), 42.6
(2C), 123.6 (2C), 123.8 (2C), 125.6 (2C), 126.2 (2C), 126.6 (2C), 127.6 (2C), 128.2 (2C), 131.3
(2C), 133.1 (2C), 149.3 (2C), 186.0 (2C). IR(KBr) 2934, 1537, 1394, 1286, 1213, 1136, 1119,
812, 751 cm–1. [α]D
22.8 = +156.1 (c 1.0, CHCl3). HRMS(FAB+) calcd for C26H24N2O2S2 [M]+
460.1279, found 460.1276.
Attached Files
Reaction Scheme MW45-1