This invention relates to compounds of formula I
their use as positive allosteric modulators of mGlu5 receptor activity, pharmaceutical compositions containing the same, and methods of using the same as agents for treatment and/or prevention of neurological and psychiatric disorders associated with glutamate dysfunction such as schizophrenia or cognitive decline such as dementia or cognitive impairment. R
1
, R
2
, R
3
, R
4
, Q have meanings given in the description.
Enantioselective reduction of representative 2-(bromoacetyl)- and 2-(chloroacetyl)benzofurans with (-)-B-chloro-diisopinocampheylborane and by transfer hydrogenation with formic acid/triethylamine in the presence of RhCl[R,R-TsD-PEN](C5Me5) is described. Transfer hydrogenation of the chloro ketones produced the corresponding chlorohydrins of >= 95% ee. (R)-Bufuralol of 96% ce was prepared from the corresponding chloro ketone by transfer hydrogenation-substitution. (c) 2005 Elsevier Ltd. All rights reserved.
v. Wacek; Eppinger; v. Bezard, Chemische Berichte, 1940, vol. 73, p. 521,528