Conformationally restricted P1-P1' transition state analogues. Synthesis of 1(R), 3(R) [1(S), 2(S)] and 1(S), 3(S) [1(S), 2(S)] 3-[3-cyclohexyl-2-[(BOC)amino]-1-hydroxypropyl]-2,2-dimethylcyclo propane carboxylic acids