. . . "In accordance with another specific embodiment of the present disclosure, in the abovementioned formula (I) or (II), Y is a protecting group known to those skilled in the art, for instance those described in the books ???Protective Groups in Organic Synthesis???, T. W. Greene, John Wiley & Sons Ed., NY, 1981, pp. 193-217; ???Protecting Groups???, P. Kocienski, Thieme, 3rd Ed., 2005, Chap. 5." . .