1-Amino-1,1-bisphosphonates. Fundamental syntheses and new developments

Amino-1,1-bisphosphonates have become increasingly important in different fields of chemistry, medicine and agriculture. The combination of the unique physical, chemical and biological properties of methylenebisphosphonate and aminophosphonate fragments opens wide possibilities for the design of biologically active compounds including therapeutic agents to treat bone disorders related to calcium metabolism, immunomodulators, anti-infectives and plant growth regulators. The scope of this review is to summarize the existing strategies for the preparation of diversely functionalized 1-amino-1,1-bisphosphonates and to illustrate their utility as synthetic building blocks.