With dplyr you would do:
library(dplyr)
df = data.frame(q = 1, w = 2, e = 3)
df %>% rename(A = q, B = e)
# A w B
#1 1 2 3
Or if you want to use vectors, as suggested by @Jelena-bioinf:
library(dplyr)
df = data.frame(q = 1, w = 2, e = 3)
oldnames = c("q","e")
newnames = c("A","B")
df %>% rename_at(vars(oldnames), ~ newnames)
# A w B
#1 1 2 3
L. D. Nicolas May suggested a change given rename_at is being superseded by rename_with:
df %>%
rename_with(~ newnames[which(oldnames == .x)], .cols = oldnames)
# A w B
#1 1 2 3