Patent ID: 7750162

Claim:
A process for the preparation of a nonnatural amino acid represented by the following formula (C): which is characterized by deprotecting protective groups of carboxyl groups in the malonic acid moiety of the compound represented by following formula (B): and then subjecting the resulting compound to elimination of two carbon dioxide molecules (step 2) to prepare said nonnatural amino acid (C), wherein R 1 is a substituted or unsubstituted aromatic group, a substituted or unsubstituted and unsaturated heterocyclic group, or R 6 CO group, R 2 and R 3 are independently a protected carboxyl group, R 4 is a protected amino group, R 5 is hydrogen atom, a substituted or unsubstituted and saturated or unsaturated aliphatic hydrocarbon group, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted and saturated or unsaturated heterocyclic group, R 6 is a substituted or unsubstituted and saturated or unsaturated aliphatic hydrocarbon group, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted and saturated or unsaturated heterocyclic group, and p, q and r are independently an integer of 0 to 10.