All Notebooks | Help | Support | About
15th March 2011 @ 05:28
Acid-catalyzed Pictet-Spengler using 10 mol% methanesulfonic acid in order to compare the results of Acid-catalyzed Pictet-Spengler reaction with binaphthalenedisulfonic acid (MW56-1 to MW56-4)

Reaction Scheme


Hazard and Risk Assessment:
HRAF MW56.pdf


See also: Continuation: Acid-catalyzed Pictet-Spengler reaction with methanesulfonic acid (MW56-9 to MW56-14)

Start time: 5:40 pm 15/03/2011
End time: 9:30 pm 16/03/2011

MW56-5:
A solution of MW29-4 (18.8 mg, 50.0 µmol, M.W. 376.5 g/mol) and methanesulfonic acid (0.48 mg, 5.0 µmol, 10 mol%, M.W. 96.1 g/mol) in toluene (1 mL) was stirred for 17 h at 70°C.
- orange solution

LCMS: unselective reaction, no specific product / starting material signals.
Data: LCMS MW56-5 (16h).pdf

MW56-6:
A solution of MW51-1 (18.5 mg, 50.0 µmol, M.W. 370.4 g/mol) and methanesulfonic acid (0.48 mg, 5.0 µmol, 10 mol%, M.W. 96.1 g/mol) in toluene (1 mL) was stirred for 17 h at 70°C.
Product, see: MW53-4
- yellow solution

LCMS: unselective reaction, no specific product / starting material signals.
Data: LCMS MW56-6 (16h).pdf

MW56-7:
A solution of MW40-1 (21.8 mg, 50.0 µmol, M.W. 436.5 g/mol) and methanesulfonic acid (0.48 mg, 5.0 µmol, 10 mol%, M.W. 96.1 g/mol) in toluene (1 mL) was stirred for 17 h at 70°C.
- brown solution

LCMS: no more starting material, two peaks with the mass of the prodcut m/z = 373 [M+H]+ (RT = 10.23, 11.15).
Data: LCMS MW56-7 (16h).pdf

MW56-8:
A solution of MW52-1 (21.5 mg, 50.0 µmol, M.W. 430.5 g/mol) and methanesulfonic acid (0.48 mg, 5.0 µmol, 10 mol%, M.W. 96.1 g/mol) in toluene (1 mL) was stirred for 17 h at 70°C.
- orange solution
Product, see: MW54-3

LCMS: no more starting material, two peaks with the mass of the prodcut m/z = 367 [M+H]+ (RT = 9.551, 10.37).
Data: LCMS MW56-8 (16h).pdf

TLC (ethyl acetate, stain: ceric ammonium molybdate):
TLC MW56-1 to MW56-8.JPG


* LCMS Method: HPLC: Waters sunfire C18; gradient A water, B acetonitrile + 0.1 % formic acid, 0 to 100%B over 15 min, flow 0.2 ml/min flow rate.

Results:
-> non-selective reaction for MW56-5 and MW56-6 (unactivated compound) - increasing the catalyst concentration
-> almost selective Pictet-Spengler reaction of both dimethoxy-substituted Ugi-intermediates
Linked Posts
Attached Files
Reaction Scheme
TLC MW56-1 to MW56-8.JPG
LCMS MW56-5 (16h).pdf
LCMS MW56-6 (16h).pdf
LCMS MW56-7 (16h).pdf
LCMS MW56-8 (16h).pdf