Reaction of 2-chloropyrazine (I) with 3,4-dichlorophenylmagnesium bromide (II) in the presence of [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride produced the 2-arylpyrazine (III), which was reduced to the corresponding piperazine (IV) by means of DIBAL in THF. In a different procedure, bromination of methyl 3,4-dichlorophenylacetate (V) using N-bromosuccinimide, followed by reaction of the resulting bromo ester (VI) with ethylenediamine (VII) afforded the piperazinone (VIII), which was further reduced to (IV) by using LiAlH4 in Et2O.

Regioselective coupling of the 2-arylpiperazine (IV) with 3,5-dimethylbenzoic acid (IX) at the less hindered N atom by means of EDC and HOBt afforded the 4-benzoyl piperazine (X). This was subsequently acylated with bromoacetyl bromide (XI) to yield the bromo amide (XII). Bromide displacement in (XII) with 4-amino-1-benzylpiperidine (XIII) then gave the title compound.

Reaction of 2-chloropyrazine (I) with 3,4-dichlorophenylmagnesium bromide (II) in the presence of [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride produced the 2-arylpyrazine (III), which was reduced to the corresponding piperazine (IV) by means of DIBAL in THF. In a different procedure, bromination of methyl 3,4-dichlorophenylacetate (V) using N-bromosuccinimide, followed by reaction of the resulting bromo ester (VI) with ethylenediamine (VII) afforded the piperazinone (VIII), which was further reduced to (IV) by using LiAlH4 in Et2O.

Regioselective coupling of the 2-arylpiperazine (IV) with 3,5-dimethylbenzoic acid (IX) at the less hindered N atom by means of EDC and HOBt afforded the 4-benzoyl piperazine (X). This was subsequently acylated with bromoacetyl bromide (XI) to yield the bromo amide (XII). Bromide displacement in (XII) with 4-amino-1-benzylpiperidine (XIII) then gave the title compound.

Reaction of 2-chloropyrazine (I) with 3,4-dichlorophenylmagnesium bromide (II) in the presence of [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride produced the 2-arylpyrazine (III), which was reduced to the corresponding piperazine (IV) by means of DIBAL in THF. In a different procedure, bromination of methyl 3,4-dichlorophenylacetate (V) using N-bromosuccinimide, followed by reaction of the resulting bromo ester (VI) with ethylenediamine (VII) afforded the piperazinone (VIII), which was further reduced to (IV) by using LiAlH4 in Et2O.

In a related method, the 2-arylpiperazine (IV) was first protected as the 4-tert-butyl carbamate (XIV) upon treatment with di-tert-butyl dicarbonate in MeOH at -78 C. Subsequent acylation of (XIV) with bromoacetyl bromide (XI) produced the bromo amide (XV), which was then condensed with the aminopiperidine (XIII), yielding the glycinamide derivative (XVI). Acidic cleavage of the Boc group of (XVI) afforded the 1-acyl piperazine (XVII). This was finally coupled with 3,5-dimethylbenzoic acid using EDC and HOBt.