Synthesis of benzocyclobutenes
A combination of Pd(OAc)2 and PtBu3 as catalyst, K2CO3 as the base, and DMF as solvent allows the synthesis of benzocyclobutenes (BCB) by C-H activation of methyl groups. Various substituted BCBs were obtained under these conditions with good yields, including molecules that are hardly accessible by other methods.
M. Chaumontet, R. Piccardi, N. Audic, J. Hitce, J.-L. Peglion, E. Clot, O. Baudoin, J. Am. Chem. Soc., 2008, 130, 15157-15166.
A new, mild, one-pot zirconium-promoted cross-coupling reaction of aryllithium compounds and alkenyl bromides allows the regio- and diastereoselective synthesis of functionalized cyclobutabenzene derivatives from simple and easily available starting materials.
J. Barluenga, J. Calleja, M. J. Antón, L. Álvarez-Rodrigo, F. Rodríguez, F. J. Fañanás, Org. Lett., 2008, 10, 4469-4471.
The photocatalytic reactions of benzoylformate esters with alkenes can be directed toward either Paternò-Büchi cycloadditions or allylic functionalization reactions under conditions favoring energy transfer or electron transfer, respectively.
J. Zheng, X. Dong, T. P. Yoon, Org. Lett., 2020, 22, 6510-6515.
Benzyne-[2+2] cycloadditions with enamides enabled the development of a highly stereoselective tandem [2+2] cycloaddition-pericyclic ring-opening-intramolecular-N-tethered-[4+2] cycloaddition for rapid assembly of nitrogen heterocycles.
J. B. Feltenberge, R. Hayashi, Y. Tang, E. S. C. Babiash, R. P. Hsung, Org. Lett., 2009, 11, 3666-3669.