Styrylmalonates as an Alternative to Donor–Acceptor Cyclopropanes in the Reactions with Aldehydes: A Route to 5,6-Dihydropyran-2-ones

A new
strategy for modifying the reactivity of donor–acceptor
cyclopropanes (DAC) has been suggested. It involves the use of isomeric
styrylmalonates as alternative sources of reactive intermediates.
The efficiency of the approach has been demonstrated in reactions
with aromatic aldehydes. As a result, a new process for construction
of the 5,6-dihydro­pyran-2-one skeleton has been developed. It
efficiently occurs with high diastereoselectivity in the presence
of BF3·Et2O; the products can be easily
isolated by crystallization. The subsequent use of the resulting dihydropyranones
in syntheses providing convenient access to various classes of compounds
with broad molecular diversity has been demonstrated.

本研究提出了一种调控给体-受体环丙烷（donor–acceptor cyclopropanes, DAC）反应活性的全新策略。该策略以异构的苯乙烯基丙二酸酯作为活性中间体的替代来源。通过与芳香醛的反应验证了该方法的有效性，由此开发出一种构建5,6-二氢吡喃-2-酮骨架的全新合成方法。该反应在BF3·Et2O存在下可高效进行，且具有优异的非对映选择性，产物可通过结晶法便捷分离。后续实验证实，利用所得二氢吡喃酮类化合物进行合成，能够便捷制备各类具有丰富分子多样性的化合物。