Motown's first single of 1972 all but declared the end of the label's life in Detroit. The B side of the Four Tops' "A Simple Game" (a Moody Blues cover, cut in London with the Moodies as the session band) was a soft-psych confection, "L.A. (My Town)." Six months later, Motown announced the closing of its hometown offices. "The Sound of Young America" was now a California business. The changes in creative focus and commercial priority that triggered, then followed, that migration are all over this five-CD set, which covers the first half of '72. It's an intriguing mess, with singles by white-pop idols at low ebb (Frankie Valli, Bobby Darin); rock-band curios like "Gypsy Eyes," by Blue Scepter, formerly the Michigan acid-rock combo SRC; and fine new work that went nowhere by Sixties Motown stalwarts such as the Originals and the Marvelettes' Wanda Rogers. Marvin Gaye's funky, urgent "You're the Man," his first new material since the epochal LP What's Going On, was a chart flop. But Michael Jackson and the Jackson 5 are in peak juvenile form (the saucy B side "Love Song"); there are sublime female-vocal rarities by the Sisters Love and the Blackberries; and the Commodores (with Lionel Richie) bust out of Tuskegee, Alabama, with the crunchy proto-disco of "The Zoo (The Human Zoo)." It wasn't a hit, but you hear the "Brick House" lurking in there.