breqn and \brace

Question

I was looking forward to using breqn, but it mysteriously fails with the following piece of code:

\begin{dmath*}
    {2 \brace 3}
\end{dmath*}

However, this construct outputs a "Missing delimiter" error (\choose works without a hitch). What gives?

I'm working with TexLive 2011 on OS X.

Answer 1

\{ has additional code so that it works in text mode as well as math and that upsets breqn in the form used here. These infix primitives are rightly deprecated with amsmath, but if you must you may:-)

\documentclass{article}

\let\oldlbrace\lbrace
\let\oldrbrace\rbrace
\def\brace{\atopwithdelims\oldlbrace\oldrbrace}
\usepackage{breqn}


\begin{document}
\begin{dmath*}
  {2 \brace 3 }
\end{dmath*}
\end{document}