A catalytic asymmetric one-pot [3+2] cyclization/semipinacol rearrangement sequence: An efficient construction of a multi-substituted 3: H -spiro[benzofuran-2,1′-cyclopentane] skeleton

Article abstract of DOI:10.1039/c9cc00811j

A facile and efficient method to form a chiral multi-substituted 3H-spiro[benzofuran-2,1′-cyclopentane] structural unit has been developed via a one-pot [3+2] cyclization/semipinacol rearrangement cascade. A catalysis system of Cu(ii)/BOX has been used to efficiently construct a key stereogenic center via a cyclization between substituted benzoquinones and allylic alcohols affording the desired products in good yields and with excellent enantioselectivities and diastereoselectivities (21 examples; up to 67% yields; up to 92% ee and up to >20:1 dr). This method provides an alternative strategy for the synthesis of the corresponding bioactive molecules containing spiro[benzofurancyclopentane] skeleton units.