研究人员针对七元环螺茚满酮衍生物合成难题，开发了DMAP催化的 [4 + 3]环化新策略，通过ninhydrin-MBH碳酸酯与无环氮杂二烯高效构建多取代螺 [indanone-azepine]骨架，收率高达98%。该方法条件温和、官能团兼容性好，为药物先导化合物开发提供了重要工具。

Alternatively, 4-DMAP and 6-DMN can be directly inserted as building blocks through their corresponding Fmoc-protected amino acids using standard Fmoc-based SPPS procedures.

The procedure utilizes anhydride precursors of 4-dimethylaminophthalimide (4-DMAP) or 6-dimethylaminonaphthalimide (6-DMN), whose syntheses are described in a related protocol from these authors.