Synthesis of Highly Strained Cyclobutane Fuels via Room-Temperature-Integrated Oxidation/[2 + 2] Cycloaddition of Lignocellulose-Based Cyclic Ketones and Cyclic Alcohols

High-energy-density cyclobutane fuels were directly synthesized via room-temperature-integrated one-pot two-step oxidation/self-photosensitized [2 + 2] cycloaddition using lignocellulose-derived cyclic ketones and cyclic alcohols for the first time, which endow much higher density, lower freezing point, and higher neat heat of combustion than other biofuels achieved from the same feedstocks and hence denote a new kind of sustainable high-density fuels appealing for practical applications.