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.