Synthesis of cyclobutenones
A tandem Michael addition/cyclic 1,2-addition/elimination of 2,3-allenoates and organozinc reagents enables the synthesis of polysubstituted cyclobutenones, which are not readily available from traditional methods due to the intrinsic ring strain. Application to the synthesis of stereodefined β,γ-unsaturated enones is demonstrated.
G. Chai, S. Wu, C. Fu, S. Ma, J. Am. Chem. Soc., 2011, 133, 3740-3743.
A one-pot synthesis of 4-amino-2-naphthol derivatives is accomplished via a ZnI2-catalyzed tandem Friedel-Crafts reaction sequence. While in the presence of Pd(0) catalyst, a [2 + 2] cycloaddition reaction of ynamides with monosubstituted ketenes provides 3-aminocyclobutenones, which were subsequently converted to 3-amino-1-naphthols.
C. Qian, K. Liu, S.-W. Tao, F.-L. Zhang, Y.-M. Zhu, S.-L. Yang, J. Org. Chem., 2018, 83, 9201-9209.