Heterocycle 1 (form B12 is an in vitro degradation product of the highly labile molybdenum cofa&r, B present in all molybdenum-containing enzymes except nitrogenase. The structural assignment of form B rests on chemical, mass spectral, and NMR data comparison with known pterins but has not been confirmed unambiguously by total~ ynthesis.~ In this paper, we report the development of a convenient synthetic method for the construction of ...
