Construction is rising on 300 East 50th Street, a 23-story residential building in the Turtle Bay section of Midtown East, Manhattan. Designed by BKSK Architects and developed by MAG Partners in collaboration with Global Holdings, KRW Realty Advisors, Krown Point, and Safanad, the 275-foot-tall structure will span 170,000 square feet and yield 194 units, with 30 percent…