Patent ID: 7531657

Claim:
A method for preparing a compound represented by the following general formula (5) where, n is an integer of 0 to 3; and Y represents a protecting group for an amino group, comprising the steps of reacting a compound represented by the following general formula (3) where, n and Y are as described above, with a sililating agent, represented by the following general formula (6) where R1, R2 and R3 each independently represent a lower alkyl group or an aryl group; and X represents a halogen atom or a fluorinated alkyl sulfonate,subsequently reacting it with a phosphorus oxyhalide represented by the general formula(4) P(═O)T 3 (4) where T represents a halogen atom and further with ammonia, wherein a reaction temperature is −20°C. to 80° in the steps of preparing a compound represented by the general formula (5) from a compound represented by the general formula (3).