Nucleophilic displacement of a benzylic bromide using sodium cyanide; (2-bromo-5-methoxy-3-methylphenyl)-acetonitrileSyntheticPage 172 (2001)
Submitted 26th Nov 2001, published 26th Nov 2001
A contribution from the Caddick Group, Sussex
2-bromo-1-bromomethyl-5-methoxy-3-methyl benzene ([SyntheticPage 156] )
Sodium cyanide (Lancaster)
To a solution of 2-bromo-1-bromomethyl-5-methoxy-3-methyl benzene (24.7g, 0.084 mol, 1 equiv) in DMSO (1.25 mL/mmol; 105 mL) was added a solution of sodium cyanide (7.4 g, 0.151 mol, 1.8 equiv) in DMSO (40 mL) by aid of a dropping funnel. The resulting golden solution was heated to 90 oC for 2 h and allowed to cool to room temperature. The resulting brown solution was poured into 1.5 L of ice water to give a fawn cloudy solution. This was extracted with ether (2.5 L in total) to give a brown solution. The combined organic layers were dried over sodium sulfate and concentrated in vacuo to yield a brown solid which was seen to be of sufficient purity for use in further stages. (17.6 g, 87%)
This reaction has been carried out numerous times within the lab on both large and small scales. We have found that the largest scale possible due to work up considerations is the scale reported above. The addition of the sodium cyanide can sometimes cause problems due to the low solubility in DMSO. This problem is easily overcome by simply adding the NaCN portionwise to a more dilute solution of the bromide. A further practical consideration is the aqueous extraction, which sometimes causes problems due to the DMSO preventing separation of the two layers. This can be overcome by the addition of a small amount of salt to the aqueous layer. NB All glasswear must be cleaned by submersion in bleach for 24 h after the reaction. Local safety rules should be consulted before working with cyanides (eg breathing apparatus, antidote etc).
1H nmr (300MHz, CDCl3) 2.41 (2H, s), 3.82 (3H, s), 3.84 (3H, s), 6.79 (1H, d, J = 2.7Hz), 6.93 (1H, d, J =2.7Hz).
Rucker, Mark; Brueckner, Reinhard; Synlett.; 1997; 1187-1189.
Goerth, Felix Christian; Rucker, Mark; Eckhardt, Matthias; Brueckner, Reinhard; Eur.J.Org.Chem.; 14; 2000; 2605 - 2612.
This page has been viewed approximately 656 times since records began.
Get CDX file (Choose "Open this file from its current location" TWICE)
SyntheticPagesTM are for use
exclusively by those with training and experience in synthetic chemistry. While contributors
are asked to identify hazards and to use methods designed to reduce risk, no formal hazard
or risk assessments are included, and these procedures must be conducted at one's own risk.
SyntheticPages, its editors, owners and associates do not warrant or guarantee the safety of
individuals using these procedures and hereby disclaim any liability for any injuries or damages
claimed to have resulted from or related in any way to the procedures herein. Copyright ©2005 Synthetic Pages
Comment on this page!
Registered users may add comments to other pages. If you have already registered, please
log in, otherwise you may
Back to List