Abstract: The invention provides a new convergent approach for the synthesis of 2?-fluoro-6?-methylene-carbocyclic adenosine (FMCA) from a readily available starting material (Vince lactam) in fourteen steps. An efficient and practical methodology for stereospecific preparation of a versatile carbocyclic key intermediate, D-2?-fluoro-6?-methylene cyclopentanol by diazotization, elimination, stereoselective epoxidation, fluorination and oxidative reduction of the Vince lactam in twelve steps is also provided.

Abstract: A method and apparatus is presented for calibrating instruments for time interval measurements, pulse width measurements, and rise and fall time measurements. The preferred method comprises generating two coherent pulses using a linear passive device. The coherent pulses are simultaneously a.c. coupled to two channels of, for example, a time-interval measuring instrument. The time interval between the coherent pulses passing through the instrument is measured at identical voltages on each signal. Then the coherent pulses are exchanged between the channels and a further interval measurement is made. The results of each of the measurements are compared and used to calculate calibration constants to correct systematic errors present in the instrument.