 The carboxylic acid produced as a result of the deprotection was then converted to an acyl chloride by oxalyl chloride and a catalytic amount of DMF.Finally, addition of sodium azide, in the last reaction of the second one-pot operation, produce the acyl azide (7) without any purification needed.The final one-pot operation begins with a Curtius Rearrangement of acyl azide (7) to produce an isocyanate functional group at room temperature.