Modular and Stereoselective Synthesis of Cyclobutane β-Amino Alcohols.

Cyclobutane β-amino alcohols are valuable structural motifs, yet their development has lagged behind that of five- and six-membered analogs due to limited synthetic accessibility. In this work, we report a general and modular strategy for the synthesis of diversely substituted cyclobutane β-amino alcohols. The electronic structure of 1,2-azaborines is leveraged to achieve regioselective mono- and difunctionalization at all four carbon positions. The installed functionalities are subsequently translated into cyclobutane β-amino alcohol frameworks through a tandem photoisomerization-hydrogenation-oxidation sequence. This strategy provides access to eight distinct substitution patterns with high levels of modularity and diastereoselectivity.