There is provided a copolyester containing residues of neopentyl glycol, 2,2,4,4-tetraalkyl 1,3-cyclobutanediol such as 2,2,4,4-tetramethyl 1,3-cyclobutanediol, tin atoms, aluminum atoms, an alkali or alkaline earth metal atoms such as lithium atoms, optionally phosphorus atoms, and having an It.V. of at least 0.55 dL/g, and Tg of at least 90° C. Such higher It.V. copolyesters can now be made having high Tg, good thermal stability, and higher insertion of 2,2,4,4-tetraalkyl 1,3-cyclobutanediol.