The L-, D-, and racemic forms of 1-hydroxyproline (1) as well as 1-hydroxy-DL-pipecolic acid (2) and N-hydroxysarcosine (3) were prepared from the respective amino acids by (a) cyanoethylation,(b) N-oxidation of 1-(2-~ yanoethyl) amino acids, and (c) elimination of acrylonitrile in a Cope elimination. 2, 3, or the L form of 1 did not inhibit the growth of L-1210 lymphoid leukemia in BDFl mice, and L-1 did not inhibit the growth of Escherichia coli B or ...