Pyrrolidines and piperidines were synthesized from (aminoalkyl)pyridine N-oxides with a general and quite efficient method developed by using di-tert-butylsilyl bis(trifluoromethanesulfonate) as a new promoter for a Boekelheide-type reaction. The use of a new Boekelheide promoter, which is compatible with amino groups, opens new perspectives in view of its application in intramolecular cyclizations.

A new synthetic pathway to the final compound 1-[(1S)-5’,11’-dihydrospiro[cyclopentane-1,10’-dibenzo[a,d]cyclohepten]-3-yl]-3-azetidinecarboxylic acid (1) was set up. The two preparative chiral HPLC separations needed in the first route were successfully avoided and replaced by two diastereomeric crystallizations of intermediate compounds 5 and 10.

A multi-technique approach was applied in order to fully characterize four low-level unknown impurities of GW876008, a novel CRF1 receptor antagonist. Liquid chromatography (LC)–NMR spectroscopy was used in combination with LC–MS to obtain detailed information regarding the structure of the two major impurities present in batches of GW876008 and observed in the first synthetic scale-up for preclinical use. Two additional impurities were unexpectedly found at greater levels in a large scale synthesis for clinical use and their structure was elucidated by means of high resolution (HR)–MS and HR–NMR, after a small scale preparative HPLC purification step. This structural information was useful in terms of shedding light on the typical impurity profile of this new chemical entity with the aim to support the early development package for Phase I clinical studies.

New enantiomerically enriched 1,4,5-piperazines and 1,4,5-dihydro-2H-pyrazines have been prepared by reduction of the corresponding 2-oxo-piperazines. Selective reduction can be achieved by careful control of the reaction conditions using LiAlH4. Notably the two nitrogen atoms of the final compounds are orthogonally protected.

An efficient scalable route to synthesize the enantiomerically pure tert-butyl-(1R,4S,6R)-4-(hydrox)methyl)-3-azabicyclo[4.1.0]heptane-3-carboxylate is described. Compared to the original routes, significant improvements were made by using an innovative approach starting from commercially available chiral lactone. In this approach, one of the key steps described is an elegant epimerization/hydrolysis of the undesired diastereoisomer avoiding tedious purification. The chemistry has been scaled up to produce kilogram amounts of tert-butyl-(1R,4S,6R)-4-(hydroxymethyl)-3azabicyclo[4.1.0]heptane-3-carboxylate in 43% yield over nine chemical transformations.

A series of AMPA receptor positive allosteric modulators has been optimized from poorly penetrant leads to identify molecules with excellent preclinical pharmacokinetics and CNS penetration. These discoveries led to 17i, a potent, efficacious CNS penetrant molecule with an excellent pharmacokinetic profile across preclinical species, which is well tolerated and is also orally bioavailable in humans.

To identify new CRF1 receptor antagonists, an attempt to modify the bis-hetherocycle moiety present in the top region of the dihydropirrole[2,3]pyridine template was made following new pharmacophoric hypothesis on the CRF1 receptor antagonists binding pocket. In particular, the 2-thiazole ring, present in the previous series of compounds, was replaced by more hydrophilic non aromatic hetherocycles able to make appropriate H-bond interactions with amino acid residues Thr192 and Tyr195. This exploration, followed by an accurate analysis of the substitution of the pendant aryl ring, enabled to identify in vitro potent compounds showing excellent pharmacokinetics and outstanding in vivo activity in animal models of anxiety, both in rodents and primates.

Exploiting the SAR of the known pyrrole derivatives, a new class of mGluR1 antagonists was designed by replacement of the pyrrole core with an indole scaffold and consequent cyclization of the C-2 position into a tricyclic beta-carboline template. The appropriate exploration of the position C-6 with a combination of H-bond acceptor groups coupled with bulky/lipophilic moieties led to the discovery of a new series of mGluR1 antagonists. These compounds exhibited a non-competitive behavior, excellent pharmacokinetic properties, and good in vivo activity in animal models of acute and chronic pain, after oral administration.

A highly stereoselective approach to 1,3,4,5- and 1,3,3′,4,5-polysubstituted 2-oxopiperazines is reported. The method is based on the synthetic elaboration of naturally occurring amino acids to obtain enantiomerically enriched C-5 substituted oxopiperazines, which are further functionalized at C-3 via enolate formation and reaction with electrophiles. Notably, the two nitrogens of the ring can be orthogonally protected.