Wharton-Grob fragmentation

The Wharton-Grob fragmentation and the cationic cyclisation of polyolefins. Synthesis o/Cecropia juvenile hormone and d, -progesterone. 

The less hindered peripheric secondary hydroxyl group of the key intermediate 28 was chemoselectively tosylated (29), submitted to an internal Wharton-Grob fragmentation (30). After attack on the carbonyl group (3i) with methyllithium and activation of the secondary alcohol as the corresponding tosylate, the resulting... 

This reaction is related to the Bamford-Stevens Reaction, Grob Fragmentation and Wharton Rearrangement. 

Table 13. Cycloheptenones by Grob- Wharton Fragmentation of Bicyclo[3.2.0]heptan-l-ol Derivatives...

A base-catalyzed Grob-Wharton fragmentation of a hydroxybicyclo[5.4.0]nonyl sulfone 3 yielded a cyclononenone derivative 4.193 The reaction is initiated by lactone cleavage with powdered potassium hydroxide in methanol, whereas sodium methoxide was not successful. 

Methoxide promoted lactone cleavage in a tricyclic sulfone initiated a Grob-Wharton fragmentation which gave a cycloundecadienone derivative 1 in refluxing methanol.210... 

This reaction type is called a Grob as well as a Wharton fragmentation [1] [2]. 

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