Having established that this transformation can tolerate various aryl-substituted substrates, we then turned our attention to the tolerance of the alkyl component. The strained alkyl-substituted β-keto esters bearing different functional groups, such as phenyl ether (3n), silyl ether (3o-3q), and ketal (3r), were evaluated. To our delight, all of the substrates smoothly provided the highly strained bicyclo[5.3.0] ring systems in good yields. It is worth mentioning that this protocol can be performed steadily on a gram scale. Thus, 1.59 g of 3n was easily synthesized from readily available 1n and 2b. Moreover, these scaffolds provided versatile synthetic handles for further modifications in natural product synthesis and drug development. In order to explore its prospective potential, this synthetic methodology was applied in the late-stage diversification of natural products and/or complex drug molecules. As shown in Table , under optimized conditions, several natural products can be decorated via our method to afford seven or enight membered polycyclic architectures. These examples further illustrated the advantage of this strategy for the functionalization of biologically active natural products, which plays a significant role in drug development.