  We propose a scheme to realize a frustrated Bose-Hubbard model with ultracold
atoms in an optical lattice that comprises the frustrated spin-1/2 quantum XX
model. Our approach is based on a square ladder of magnetic flux close to $\pi$
with one real and one synthetic spin dimension. Although this system does not
have geometrical frustration, we show that at low energies it maps into an
effective triangular ladder with staggered fluxes for specific values of the
synthetic tunneling. We numerically investigate its rich phase diagram and show
that it contains bond-ordered-wave and chiral superfluid phases. Our scheme
gives access to minimal instances of frustrated magnets without the need for
real geometrical frustration, in a setup of minimal experimental complexity.
