I worked in Harlem throughout the 90s. I remember several churches that previously had been synagogues as attested by carvings in the stone edifices.
Harlem itself was once an Italian & Jewish neighbothood.
Yes, Google tells us the black Jews of Harlem are still alive and well. http://www.blackpast.org/aah/black-jews-harlem
I knew a member of such a Congregation. One of the greatest people I ever met.