Coenzyme models. 48. Novel diastereo-differentiating hydrogen transfer and "rope-skipping" racemization in chiral flavinophanes and 5-deazaflavinophanes
of 5-deazaisoalloxazinophanes dFl(n) in which N(3) and O(2′α) in the 10-(2-hydroxy)phenyl group were linked by a (CH2)n chain (n= 6,8) resulted in the boat-shaped 1,5-dihydro forms dFlred(n); hydrogentransfer to dFl(n) and from dFlred(n) occurred exclusively at the axial C(5) position.