Many yuppies lived on the Upper West Side, so it was called the "Yupper West Side." The ProQuest Historical Newspapers database show nine hits for "Yupper West Side," but all are from the 1980s.
"Yupper West Side" is both a dated and a derogatory term.
21 August 1985, Washington Post, pg. A3:
In an op-ed piece in The New York Times, a resident of the neighborhood now known as the "Yupper West Side," warned people not to park on Riverside Drive along the Hudson River, where three-bedroom apartments sell for close to $1 million.
6 September 1985, Washington Post, pg. WE11:
And if the detached feeling and incongruously glossy costumes make this look more like a Yupper West Side story, it's still a pleasure to hear these songs again, and see the original staging concepts and Robbins' rule-breaking choreography.