Ketones carbonyl ylide generation

The carbonyl ylide generated from metal carbene can also add to C=0 or C=N bonds. The [2 + 3]-cycloaddition of carbonyl ylide with G=0 bond has been used by Hodgson and co-workers in their study toward the synthesis of zaragozic acid as shown in Scheme n 27a,27d Recently, a three-component reaction approach to syn-a-hydroxy-f3-amino ester based on the trapping of the carbonyl ylide by imine has been reported.The reaction of carbonyl ylide with aldehyde or ketone generally gives l,3-dioxolanes. Hu and co-workers have reported a remarkable chemoselective Rh2(OAc)4-catalyzed reaction of phenyl diazoacetate with a mixture of electron-rich and electron-deficient aryl aldehydes. The Rh(ii) carbene intermediate reacts selectively with electron-rich aldehyde 95 to give a carbonyl ylide, which was chemospecifically trapped by the electron-deficient aldehyde 96 to afford 1,3-dioxolane in a one-pot reaction (Equation (12)). 

Heterocycles by Cycloadditions of Carbonyl Ylides Generated from Diazo Ketones... 

Synthesis of endo spiro-oxabicyclo[3.2.l]octan-2-ones 85 has been reported based on the reaction of the six-membered ring carbonyl ylide generated from the diazo ketone 80 with cr-methylene ketones (Scheme 25) [88]. Importantly, the reverse stereoselectivity was observed between the reactions involving five-membered ring carbonyl ylide intermediates and 66, which led to exo spiro compounds (see Scheme 19). 

Muthusamy S, Krishnamurthi J (2008) Heterocydes by Cydoadditions of Carbonyl Ylides Generated from Diazo Ketones. 12 147-192... 

S. Muthusamy, J. Krishnamurthi, Heterocycles by cycloadditions of carbonyl ylides generated from diazo ketones. Top. Heterocycl. Chem. 

Interaction of a carbonyl group with an electrophilic metal carbene would be expected to lead to a carbonyl ylide. In fact, such compounds have been isolated in recent years 14) the strategy comprises intramolecular generation of a carbonyl ylide whose substituent pattern guarantees efficient stabilization of the dipolar electronic structure. The highly reactive 1,3-dipolar species are usually characterized by [3 + 2] cycloaddition to alkynes and activated alkenes. Furthermore, cycloaddition to ketones and aldehydes has been reported for l-methoxy-2-benzopyrylium-4-olate 286, which was generated by Cu(acac)2-catalyzed decomposition of o-methoxycarbonyl-m-diazoacetophenone 285 2681... 

For A-(trimethylsilylmethyl)-5-methylisothioureas 262, cycloaddition with carbonyl compounds results in 2-aminooxazolines 263. ° Aliphatic and aromatic aldehydes and ketones can be employed successfully. However, reaction with ketones appears to be poor. Ylide generation with CsF is the method of choice although TBAF and KF have also been used but with lower yields. A polar solvent such as MeCN, DMF, or hexamethylphosphoric triamide (HMPA) is required for a succesful reaction (Scheme 8.73). 

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