“…In compound 4, two methyls (δ H 2.12, br d, J ) 7.2 Hz, H-4′; δ H 1.94, dd, J ) 7.3, 1.3 Hz, H-4′′) showed the bigger coupling constants, which were coupled with H-3′ and H-3′′, respectively, and a methyl (δ H 1.85, br d, J ) 1. 3 Hz, H-5′′) showed a small coupling constant, which should be coupled with H-3′′. However, for compound 5, only a methyl (δ H 2.00, dd, J ) 7.2, 1.3 Hz, H-4′′) showed a bigger coupling constant, and the other two methyls (δ H 1.91, br s, H-5′; δ H 1.97, br d, J ) 1.…”