Cycloaddition of carbonyl ylide

Fig. 4.14. Preparation of polycyclic compounds by intramolecular 1,3-dipolar cycloaddition of carbonyl ylides to alkenes 11301].

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)). 

Intramolecular Cycloadditions of Carbonyl Ylides W. Eberbach, J. Brokatzky and H. Fritz, Angew. Chem., Int. Ed. Engl., 1980, 19, 47-48. a,(3-Unsaturated Heteroatomic Compounds in 1,3-Dipolar Addition Reactions V. A. Galishev, V. N. Chistokletov and A. A. Petrov, Russ. Chem. Rev. (Engl. Transl.), 1980, 49, 880-892. 

Dihydrofurans are valuable synthetic compounds. Nevertheless, little is known about intramolecular cycloaddition of carbonyl ylides to alkynes. In one example, alkynyl pyran-4-one (233) was cyclized to dihydrofuran (234 Scheme 69).128 Possibly this reaction proceeds via an oxidopyrylium ylide intermediate as shown. 

The Rh2(OAc)4-catalysed reactions of ethyl diazoacetate with substituted benzalde-hydes yielded 1,3-dioxolanes via an initially formed carbonyl ylide. Catalyst-dependent diastereo-control was observed only when p-mtxobenzaI dchydc was used as catalyst.104 The intramolecular cycloaddition of carbonyl ylide dipoles with tethered alkenyl 71-bonds is greatly enhanced by placing an sp1 centre on the tethered side-chain.105 The thermal reaction of 3-phenyloxirane-2,2-carbonitrile and 2-phenyl-3-thia-l-azaspiro-[4,4]non-l-ene-4-thione yields cis- and trans-cycloadducts via a regioselective 1,3-dipolar cycloaddition of an intermediate carbonyl ylide.106... 

A review about the rearrangement and cycloaddition of carbonyl ylides generated from a-diazo compounds is available <2001CSR50>. Enantioselective intramolecular cyclopropanations of allyl 2-diazo-3-silanyloxybut-3-enoates to yield cyclopropyl 7-butyrolactones have been investigated with a variety of chiral rhodium catalysts. The best results were obtained with Rh2(PTTL)4, where enantioselectivity culminated at 89% ee (Equation 99) <2005TA2007>. 

Cycloadditions of carbonyl ylides, generated from the reaction of carbenes with heteroatom lone pairs have been reviewed (91ACR22,91CRV263). 

Muthusamy and coworkers [67, 68] have examined the regioselectivity (with respect to dipole orientation) of intermolecular cycloadditions of carbonyl ylides with a variety of N-substituted indoles. l-Diazo-3,3-dimethylpentane-2,4-dione (126), upon treatment with rhodium (11) acetate and simple indole derivatives (125), might be expected to give a mixture of regioisomers 127 and 128 however, only hexahydro-2//-carbazol-2-ones 127 were observed in 86-97% (Scheme 31). 

Muthusamy S, Gunanathan C et al (2004) Regioselective synthesis of mono- and bis-decahy-drobenzocarbazoles via tandem reactions of a-diazo ketones. Tetrahedron 60 7885-7897 Nambu H, Hikime M et al (2009) Asymmetric approach to the pentacyclic skeleton of aspidosperma alkaloids via enantioselective intramolecular 1,3-dipolar cycloaddition of carbonyl ylides catalyzed by chiral dirhodium(II) carboxylates. Tetrahedron Lett 50 3675-3678... 

Chapter 4 concerns the cycloaddition of carbonyl ylides generated from diazo carbonyl compounds and rhodium or copper catalysts. In this framework chemoselective and enantioselective transformations leading to the formation of various heterocycles such as tetrahydrofurans, oxazolidines, mesoionic and bicyclic compoxmds, alkaloids, and other natural products are described. 

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

Herein rhodium-catalyzed inter- and intramolecular cycloadditions of carbonyl ylides derived from a range of diazocarbonyl compounds leading to oxygen- and nitrogen-containing heterocyclic systems and natural products are discussed. We have focussed on the last five years for the most significant developments of the reactions of carbonyl ylides derived from diazocarbonyl compounds. 

Metal-carbenoid intermediates derived from diazo compoimds undergo a variety of useful reactions, including yUde formation, cyclopropanation and insertion. In recent years, several excellent reviews [1-19] and books [20-29] have appeared on various aspects of this chemistry. Several reviews on car-benoid chemistry have major sections on 1,3-dipolar cycloadditions of carbonyl ylides. Because of the historical central prominence of carbenoids derived from diazocarbonyl compounds, most reviews have tended to focus on these species. These carbenoids are capable of generating carbonyl ylide dipoles via inter- or intramolecular reactions (Fig. 1). 

The results suggest that the Lewis acid controls the stereoselectivity in the 1,3-dipolar cycloaddition of carbonyl ylides by coordination to the dipo-larophiles, as reported [105,106] for the reactions of nitrones. 

Oxazabicyclo[2.2.1]heptan-5-one ring systems were constructed via the cycloaddition of carbonyl ylides with imines. Muthusamy and co-workers have... 

SCHEME 5.14 1,3-Dipolar cycloaddition of carbonyl ylides with ethene and ethyne. 

The cycloaddition of carbonyl ylides with electron-deficient and conjugated aUtenes are dipole-HOMO controlled. The carbon atom of the ylide HOMO, which has the largest atomic orbital coefficient, attacks the terminal carbon of the alkene, which has the largest LUMO coefficient. The fact that the reaction of the unsymmetrical dipolarophile gives a 2 1 mixture of two regioisomers indicates that in the HOMO of the carbonyl ylide, the electron density at the unsubstituted carbon is greater than that at the substituted carbon atom. 

Scheme 13.26 catalytic asymmetric 1,3-dipolar cycloaddition of carbonyl ylide promoted by Yb(OTf)3/PyBOX. 

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

Padwa et al. have applied the 1,3-dipolar cycloaddition of carbonyl ylide 120 to cylopent-2-en-l-one to generate oxanorbomanone 121 as a 4 1 mixture of exo- and enifo-isomers. The process starts with the reaction of diazoketone 119 with Rh2(OAc)4 [155, 156] (Scheme 17). 

Scheme 17 Synthesis of 7-oxanorobomanes through 1,3-dicarbonyl cycloaddition of carbonyl ylides...

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