  Multilayer (TiO$_2$)$_m$/(VO$_2$)$_n$ nanostructures ($d^1$ - $d^0$
interfaces with no polar discontinuity) show a metal-insulator transition with
respect to the VO$_2$ layer thickness in first principles calculations. For $n$
$\geq$ 5 layers, the system becomes metallic, while being insulating for $n$ =
1 and 2. The metal-insulator transition occurs through a semi-Dirac point phase
for $n$ = 3 and 4, in which the Fermi surface is point-like and the electrons
behave as massless along the zone diagonal in k-space and as massive fermions
along the perpendicular direction. We provide an analysis of the evolution of
the electronic structure through this unprecedented insulator-to-metal
transition, and identify it as resulting from quantum confinement producing a
non-intuitive orbital ordering on the V $d^1$ ions, rather than being a
specific oxide interface effect. Spin-orbit coupling does not destroy the
semi-Dirac point for the calculated ground state, where the spins are aligned
along the rutile c-axis, but it does open a substantial gap if the spins lie in
the basal plane.
