One shot pulse generator Low->High->Low even if button is still pressed?
Figure 1. Adding C1 prevents hold-on problems. Image source: Homemade Circuits.
How it works:

Before PB is pressed R1 charges the left side of C1 to V+ and R2 charges the right side. Both will be at +9 V.
When PB is pressed the left side of C1 is pulled to GND. The right side is pulled down to GND as well but immediately starts to charge up to +9 V via R2 even if PB is held.
D1 and D2 prevent pin 2 ever seeing V &gt; 9 V or V &lt; 0 V.

See the linked article for more.