PEP 1 substrate in the enolase rea~ tion~,~ and to serve as a weak competitive inhibitclr of rabbit muscle pyruvate kina~ e.~ Later, in 1976, Davidson and Kenyon reported some new synthetic approaches to 1 and made unambiguous assignments of the vinyl protons in its NMR spectrum. l In this paper, we report the preparation of a series of substituted analogules of PEP which, by virtue of being geometrically defined and conformationally ...