The gist of Obama care is that it forces unwilling people to enter into interstate commerce and purchase a product against their will.
There is an historic precedent for forcing people to enter into interstate commerce against their will: That historic precedent is SLAVERY.
Slaves were forced, against their will, to be part of (1) the slave trade and (2) to produce cotton, tobacco and other products, for the purpose of interstate commerce.
Forcing unwilling people to purchase products in interstate commerce is not different morally or constitutionally from forcing unwilling people to produce products (i.e. cotton) for entry into interstate commerce.
The precedent for Obama care is slavery.