Polycyclic Ring Formation Using Bis-diazolactams for Cascade Stitching

The
chemoselective reaction of donor/acceptor (D/A) and acceptor/acceptor
(A/A) diazo moieties in the same molecule was examined using 3-diazo-1-(ethyl
2-diazomalonyl)­indolin-2-one under rhodium­(II) catalysis. The metallo
carbenoid derived from the D/A diazo group is preferentially formed
and undergoes selective CH, NH, and OH insertion reactions, cyclopropanation,
cyclopropenation, sulfur ylide formation/2,3-sigmatropic rearrangement,
as well as nitrogen ylide formation followed by azetidine ring expansion.
The initial reaction can be paired with a subsequent tandem cascade
sequence involving dipole formation/cycloaddition in either an intra-
or intermolecular sense to generate polycyclic N-heterocycles
in one pot, with the formation up to three new rings in a single operation.
Excellent diastereoselectivity was observed in the intramolecular
cycloaddition reaction producing 5 to 7-membered rings.

本研究探讨了在同一种分子中，供体/受体（D/A）和受体/受体（A/A）偶氮基团的化学选择性反应，该研究采用3-偶氮-1-（乙基2-偶氮马来酰）-茚满-2-酮，在钌（II）催化下进行。从D/A偶氮基团衍生出的金属卡宾化合物优先形成，并经历选择性CH、NH和OH插入反应、环丙烷化、环丙烯化、硫叶立德形成/2,3-σ型重排，以及氮叶立德形成并随后进行氮杂环丁烷环扩张。初始反应可以与后续的串联级联序列相匹配，该序列涉及偶极形成/分子内或分子间环加成反应，以在单步操作中生成多环N杂环化合物，形成多达三个新的环。在分子内环加成反应中观察到优异的立体选择性，该反应产生5至7成员的环。