Cyclopropenones CPNs

Reliable synthetic methods used to prepare CPNs 56 have been developed during the past two decades, and they are classified as falling into four categories  

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Since the first synthesis of a CRN derivative, diphenylcyclopropenone 55, reported independently in 1959 by Breslow and Vol pin [30, 31], the unique and diverse reactivities of CPNs 56 and cyclopropenone acetals (CPNA) 57 have been extensively explored (Figure 6.8) [17, 32]. Today, 56 and 57 can be regarded as versatile synthetic building blocks. Furthermore, the recent discovery of CPN-containing natural products as well as CPN-based protease inhibitors renewed interest in this class of cyclic ketones [33]. 

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