Results are presented from a search for a W′ boson using a dataset corresponding to 5.0 fb−1 of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at View the MathML source. The W′ boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W′→tb, leading to a final state signature with a single electron or muon, missing transverse energy, and jets, at least one of which is identified as a b-jet. A W′ boson that couples to the right-handed (left-handed) chiral projections of the fermions with the same coupling constants as the W is excluded for masses below 1.85 (1.51) TeV at the 95% confidence level. For the first time using LHC data, constraints on the W′ gauge couplings for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.