Synthesis of 4-hydroxymethyl-2,4-methanoproline

The synthesis of 4-hydroxymethyl-2,4-methanoproline, a novel conformationally restricted amino acid, was performed in four steps. This close analogue of naturally occurring amino acids (i.e., proline, hydroxyproline, serine and threonine) was prepared in good overall yield through two intramolecular recyclization reactions of cyclobutane derivatives.