Carbonyl ylides ketone derivation

On the basis of the 1,3-dipolar cycloaddition of 5-membered ring carbonyl ylides, syntheses of oxabicyclo[2.2.1]heptan-2-one ring systems were successfully accompUshed. For example, the reactions of the cyclopropyl-substituted five-membered ring carbonyl ylide 48 derived from the a-diazo ketone 47 with different dipolarophiles have been investigated [78-80]. The compound 47 undergoes cycloaddition in the presence of Rh2(OAc)4 with dimethyl maleate, dimethyl fumarate, cyclopentenone, 1,1-dimethoxyethylene and bi-cyclopropylidene furnishing the expected cycloadducts 49-53, respectively... 

A further study on six-membered ylide formation examined the use of an aliphatic ester in place of a ketone as the Lewis base donor for carbonyl ylide formation. Although the same keto-substituted system underwent an intramolecular cyclization readily, the ester derivative gave no cycloaddition products. Padwa and co-workers (37,76) points to the major electronic differences between the two carbonyl groups to rationalize the disparity in carbonyl ylide formation. 

While most of the initial studies have involved the transition metal-catalyzed decomposition of a-carbonyl diazo compounds and have been reviewed [3-51], it appears appropriate to highlight again some milestones of these transformations, since polycyclic structures could be nicely assembled from acyclic precursors in a single step. Two main reactivities of metalo carbenoids derived from a-carbonyl diazo precursors, namely addition to a C - C insaturation (olefin or alkyne) and formation of a ylid (carbonyl or onium), have been the source of fruitful cascades. Both of these are illustrated in Scheme 27 [52]. The two diazo ketone functions present in the same substrate 57 and under the action of the same catalyst react in two distinct ways. The initially formed carbenoid adds to a pending olefin to form a bi-cyclop. 1.0] intermediate 58 that subsequently cyclizes to produce a carbonyl ylide 59, that is further trapped intramolecularly in a [3 + 2] cycloaddition. The overall process gives birth to a highly complex pentacyclic structure 60. 

K and in the solid state. The cyclic carbonyl ylide (77 R = Ph), obtained by irradiation of 2.3-diphenylnaphthoquinone 2,3-epoxide (78 R = Ph), has been trapped with suitable dipolarophiles. The carbonyl ylide (77 R = Me), derived from the 2,3-dimethyloxiran (78 R = Me) by irradiation in benzene, adds to allyl alcohol to give the hemiketal (79) by way of adduct 80. Other 2,3-dialkylnaphthoquinone 2,3-epoxides undergo similar photo-chemically induced carbon carbon bond cleavages to give dipolar or biradical species that have been trapped in turn with alkenes and ketones ... 

An efficient protocol for the synthesis of syn-facially bridged norbornane frameworks has been developed via the tandem cyclization-cycloaddition reactions of the carbonyl ylide 57 with norbornene derivatives. The reaction of the diazo ketone 56 with the dipolarophile 62 in the presence of Rh2(OAc)4 furnished [85] the 5y -facially bridged oxa-norbornane framework 63 in high yield (Scheme 17). 

Hashimoto and co-workers have shown the enantioselective 1,3-dipolar cycloaddition of the ester-derived carbonyl ylides using chiral dirhodium(II) carboxylates [110]. The ester-derived carbonyl ylide from the a-diazo ketone 98 in the presence (1 mol%) of Rh2(S-PTTL)4 99 as the catalyst afforded the cycloadduct 100 with 93% ee (Scheme 30). 

Another successful catalytic enantioselective 1,3-dipolar cycloaddition of Qf-diazocarbonyl compounds using phthaloyl-derived chiral rhodium(II) catalysts has been demonstrated [ill]. Six-membered ring carbonyl ylide formation from the a-diazo ketone 80 and subsequent 1,3-cycloaddition with DMAD under the influence of 1 mol % of dirhodium(II) tetrakis[M-benzene-fused-phthaloyl-(S)-phenylvaline], Rh2(S-BPTV)4 101 [112], has been explored to obtain the cycloadduct 102 in up to 92% ee (Scheme 31). 

In 1999, Hashimoto and coworkers demonstrated the first successM examples of the intermolecular cycloadditions of carbonyl ylides derived from a-diazo ketones with dimethyl acetylenedicarboxylate (DMDA) using fV-benzene-fitsed phthaloyl-(5)-valine-derived Rh catalyst, Rh2(5-BTPV)4 with high enantioselectivity (up to 92% ee) (Scheme 7.21) [57]. 

They also reported high levels of enantioselection for the inter-molecular cycloadditions of ester-derived carbonyl ylides with DMAD (up to 93% ee, Rh2(S-PTTL)4) (Scheme 7.22) [58] and a-diazo ketone-derived carbonyl ylides with aromatic aldehydes (up to 92% ee, Rh2(S-BTPV)4) (Scheme 7.21) [59]. Dirhodium (II) tetrakis[A -tetrachIorophthaIoyI-(S)-ferf-Ieucinate], Rh2( 5-TCPTTL)4, was found to be an exceptionally effective catalyst for tandem carbonyl ylide formation/cycloaddition reactions of... 

---