  Baryon to meson transition distribution amplitudes (TDAs), non-diagonal
matrix elements of the nonlocal three quark operator between a nucleon and a
meson state, extend the concept of generalized parton distributions. These
non-perturbative objects which encode the information on three quark
correlations inside the nucleon may be accessed experimentally in backward
meson electroproduction reactions. We suggest a general framework for modelling
nucleon to pion (pi N) TDAs employing the spectral representation for pi N TDAs
in terms of quadruple distributions. The factorized Ansatz for quadruple
distributions with input from the soft-pion theorem for pi N TDAs is proposed.
It is to be complemented with a D-term like contribution from the nucleon
exchange in the cross channel.
  We present our estimates of the unpolarized cross section and of the
transverse target single spin asymmetry for backward pion electroproduction
within the QCD collinear factorization approach in which the non-perturbative
part of the amplitude involves pi N TDAs. The cross section is sizable enough
to be studied in high luminosity experiments such as J-lab@12GeV and EIC.
