Acceptor/Acceptor‐Substituted Diazo Reagents for Carbene Transfers: Cobalt‐Catalyzed Asymmetric Z‐Cyclopropanation of Alkenes with α‐Nitrodiazoacetates

Cyclopropanation Reactions Mediated by Group 9 Metal Porphyrin Complexes

“…The catalytic system showed an excellent efficiency also with use of diazosulfones, [76] α-nitrodiazoacetates, [80] succinimidyl diazoacetate [81] and α-cyanodiazoacetate [82] (Figure 7). The synthesis of cyclopropanes bearing the different R and RЈ groups listed in Figure 7 represents an important synthetic result for several reasons.…”

Cobalt(II)‐Catalyzed Asymmetric Olefin Cyclopropanation with α‐Ketodiazoacetates

“…[6a,6b,6d,14] Increasing evidence supports that the Co(II)-based metalloradical cyclopropanation proceeds with stepwise radical mechanism and possesses a distinct reactivity and selectivity profile from electrophilic cyclopropanation by the widely studied Rh 2 - and Cu-based closed-shell systems. [15] To date, Co(II)-based metalloradical catalysis (MRC) has been shown to be effective for asymmetric cyclopropanation reactions of different types of olefins with several classes of diazo reagents, including acceptor/acceptor-substituted diazo reagents such as α-cyanodiazoacetates (CDA) [6b] and α-nitrodiazoacetates (NDA) [6d] . To further exploit the unique potential of Co(II)-MRC, we began to investigate the possibility of [Co( D 2 -Por*)]-based catalysts for asymmetric cyclopropanation using acceptor/acceptor-substituted diazo reagents beyond CDA and NDA.…”

“…The cobalt(II) complex of the D 2 -symmetric chiral porphyrin 3,5-Di t Bu-ChenPhyrin, [Co( P1 )] (Figure 1a), was shown to be an effective catalyst for asymmetric cyclopropanation with NDA [6d] and CDA. [6b] Its catalytic effectiveness toward these two acceptor/acceptor-substituted diazo reagents was attributed to the double hydrogen bonding interactions between the amide N–H donors on the P1 ligand and two acceptors on the carbene moiety in the postulated metallocarbene radical intermediate.…”

“…[6b] Its catalytic effectiveness toward these two acceptor/acceptor-substituted diazo reagents was attributed to the double hydrogen bonding interactions between the amide N–H donors on the P1 ligand and two acceptors on the carbene moiety in the postulated metallocarbene radical intermediate. [6b,6d] Since the C=O unit of ketone groups is also known as a suitable hydrogen bond acceptor, we hypothesized the potential existence of similar double hydrogen bonding interactions in the resulting cobalt-carbene radical intermediate from the reaction with KDA (Figure 1b). This hypothesis prompted us for a systematic effort to examine asymmetric cyclopropanation with common α-acetodiazoacetates using styrene ( 1a ) as a model substrate (Table 1).…”

Asymmetric Cyclopropanation of Alkenes with Dimethyl Diazomalonate Catalyzed by Chiral Diene–Rhodium Complexes

“…A bis(oxazoline) rhodium(II) complex was reported as a rare monomeric rhodium catalyst for the asymmetric cyclopropanation of alkenes with ethyl diazoacetate. [9,10] There have been many successful reports on the asymmetric cyclopropanation of alkenes with diazo compounds, [11][12][13] but the reaction with metal carbenes of malonate groups remains to be developed although the enantioenriched cyclopropane gem-diesters are very useful in total synthesis. [14] Diazomalonate derivatives are substantially less reactive toward the transition-metal-mediated decomposition leading to metal-carbene species.…”