Ketone is an important structural moiety in organic chemistry due to its wide occurrence in organic compounds and the highly transformable ability into other functionalities. Therefore, the efficient synthesis of ketones is of great significance. Recently, the ring-opening functionalization of tert-cyclobutanols represents one of the most important approaches to synthesize γ-substituted alkyl ketones. A variety of functional groups can be efficiently introduced to the γ-position of carbonyl via the regioselective C—C bond cleavage and a new chemical bond (C—C, C—N, C—O, C—F, etc.) formation. Two major pathways might be involved in the ring-opening reactions of tert-cyclobutanols: a) transition metals, such as Pd(Ⅱ) and Rh(Ⅰ), catalyzed β-carbon elimination of tert-cyclobutanols, and b) radical-mediated ring opening via the single electron oxidation of tert-cyclobutanols. The recent advances in the ring openings of tert-cyclobutanols and the related mechanistic details are described in this review.

Contents
1 Introduction
2 Transition-metal catalyzed ring openings of tert-cyclobutanols via β-carbon elimination
2.1 Pd-catalyzed ring-opening reactions of tert-cyclobutanols
2.2 Rh-catalyzed ring-opening reactions of tert-cyclobutanols
3 Radical-mediated ring openings of tert-cyclobutanols
3.1 Oxidative ring opening of tert-cyclobutanols to construct carbon-carbon bond
3.2 Oxidative ring opening of tert-cyclobutanols to construct carbon-heteroatom bonds
4 PIDA-mediated ring-opening hydroxylation of tert-cyclobutanols via carbocation pathway
5 Conclusion and outlook