About defb*{begin{align*}}

The technote document explains why this kind of shorthand definitions will fail:

6   Why can’t I use abbreviations for begin{align} ... end{align}?

Authors often like to use abbreviations such as beq eeq for begin{equation} end{equation}. For some environments defined by the amsmath package, such as align, gather, multline, and others of the same general type, this does not work: An attempt to define bal eal as shorthand for begin{align} end{align} will fail with a puzzling error message. This has to do with unfortunately nontrivial technical complications: the given environments must read their contents as a delimited macro argument because they do multipass processing of the contents using algorithms inherited from Spivak’s amstex.tex. The obvious solution-substitution of different algorithms that do box shuffling instead of token shuffling for the multipass calculations-would require rewriting these display environments from the ground up; while that is a worthy goal, it was beyond the original scope of the AMS-LaTeX project. Work is under way on an auxiliary package called breqn that addresses not only this problem but a number of others; at the time of this writing, however [September 1999] it has only progressed as far as a beta release.

Some workarounds:

• defbal#1eal{begin{align}#1end{align}}
• Define newcommand{env}[2]{begin{#1}#2end{#1}} and then use env{align}{...}