Substituted pyrazoles are well-known as pharmacologically privileged scaffolds for a diverse class of biologically relevant targets. Specifically, the five-membered pyrazole heterocycles have been of interest to the drug discovery community. Recently, C4-Chloro (4-ClPyCN) and C4-Fluoropyrazolyl-α-aminonitrile (4-FPyCN) improved the overall pharmacokinetic/pharmacodynamic (PK/PD) profile of diacylglycerol acyltransferase-2 (DGAT-2) inhibitors, leading to (i) suppression of de novo lipogenesis, (ii) improved plasma lipid profile, (iii) reduction in hepatic fat accumulation, and (iv) improved glycemic control in patients with metabolic disease. Pfizer reported DGAT-2 inhibitor, PF06424439 with a 4-ClPyCN motif tethered to its core imidazopyridine skeleton via a three dimensional (3D) cyclopropyl spacer (Fig ). PF06424439 contained 4-ClPyCN or 4-FPyCN that are less suitable, in general, for coupling to any external entity of interest to develop heterobifunctional molecules for targeted inhibition of DGAT-2. In contrast, given the synthetic viability of conjugating 4-BrPyCN or 4-IPyCN analogs using metalcatalyzed cross-coupling strategies, we planned the synthesis of Br-DGAT2 (Fig. ) to design a heterobifunctional platform for targeted DGAT-2 inhibition (Fig. ). We synthesized Br-DGAT2 following the synthetic route as shown in Figure . However, upon reaction, 4-BrPyCN yielded an unanticipated product namely, C4-Bromovinyl pyrazole (Py-N-ene) instead of the expected product, C4-Bromopyrazolyl cyclopropane carbonitrile (Fig. ).. We subjected 4-IPyCN to the same experimental conditions to understand the differential chemical reactivity of halogens under same reductive reaction environment. Surprisingly, 4-IPyCN yielded the expected C4-Iodopyrazolyl cyclopropane carbonitrile that is different from 4-BrPyCN (Scheme 1). Previously, the synthesis of Py-N-ene was reported via a facile basemediated dehydrohalogenation reaction. Herein, we have observed the formation of Py-N-ene from 4-BrPyCN despite the availability of free nucleophilic nitrogen sites within the heterocyclic substrate.