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Please login to access the full content or check if you have access via Method 7: Cyclobutanones by [2+2] Cycloaddition of Monoalkylketenes with Alkenes and Dienes

DOI: 10.1055/sos-SD-023-00535

Tidwell, T. T.Science of Synthesis, (200623603.

In 1907, Staudinger reported the [2+2] cycloaddition of ketenes with cyclopentadiene,[‌119‌] and such cyclobutanone-forming reactions have remained a mainstay of ketene chemistry. The reactions occur with bonding of the more nucleophilic carbon of the alkene to the central carbon of the ketene, and almost always give products with retention of the alkene stereochemistry and, usually, with cis-stereochemistry of the more sterically demanding substituents at the newly formed bond between the terminal carbon of the ketene and the less nucleophilic carbon of the alkene. Because of their stereoselectivity, these reactions are extremely useful in synthesis and they are the subject of a number of reviews.[‌26‌,‌120‌‌125‌] The causes of the stereoselectivity have also elicited much mechanistic study.[‌126‌‌138‌]

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Meeeee 88 Meeeeeeeeeeee Meeeeeeee eeee (8-Meeeeeeeeeee)eeeeee ee [8+8] Meeeeeeeeee eeee ee Meeeeeeeeeee[‌888‌]

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8-eeee-Meeeeeeeeeee[8.8.8]eeee-8-ee-8-eee (888, M8=e-Me); Meeeeee Meeeeeeee:[‌88‌]

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8-(Meeeeeeeeeeeeeeee)-8-(8-eeeeeeeeeeee)-8-eeeeeeeeee[8.8.8]eeeeee-8-eee (888); Meeeeee Meeeeeeee:[‌888‌]

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