Cyclization of rhodium carbenoids using ester and amido carbonyl groups

Tandem Cyclization‐Cycloaddition Reactions of Rhodium Generated Carbenoids from α‐Diazo Carbonyl Compounds.

“…The reaction of the diazo ester 72 under standard Rh(II)-catalyzed conditions results in the formation of the ylide 73 which undergoes smooth cycloaddition with a variety of dipolarophiles such as DMAD, maleic anhydride, N-phenylmaleimide and 1,1-diethoxyethylene to afford the corresponding cycloadducts. 51 The adduct 74 being readily formed from 72 with maleic anhydride (Scheme 22). An intramolecular variation (75!76) of the ester carbonylderived ylide has also been reported 51 …”

“…51 The adduct 74 being readily formed from 72 with maleic anhydride (Scheme 22). An intramolecular variation (75!76) of the ester carbonylderived ylide has also been reported 51 …”

Preparation of 2-diazo-2-oxopiperidin-3-yl-3-oxopropanoates. Useful reagents for Rh(II)-catalyzed cyclization-cycloaddition chemistry

“…The general reaction investigated is illustrated in Scheme 1; variations in chain length (n = 0, 1, 2) and nature of the activating group (G) were explored. 9 With limited exceptions, 10 alkyl and aryl ketones were employed and dipole 5 was generated by the rhodium(II)-catalyzed decomposition of the diazoalkanedione in benzene at 80 ºC. Rh(II)…”

Urea Insertion Reaction of Rhodium-Carbenoid

“…26) Metal carbenoids can also form N-ylide species with a less nucleophilic amide nitrogen, 27) and O-ylide with an amide group contributes to cycloaddition reactions as a 1,3-dipole to construct complex molecular frameworks. 28,29) As part of our ongoing studies, we developed amide insertion reactions of metal carbenoids that proceed via the initial formation of a rhodium-associated N-ylide intermediate with an amide nitrogen followed by N C acyl group transfer [30][31][32] (Chart 1(a)). In the amide insertion reaction, the amide group is activated by ylide formation with an electron-deficient metal carbenoid and hydrogen-bond network 33,34) between the substrate and catalyst so that the C−N bond is cleaved under mild conditions, 30) although amide linkage is inherently robust and its transformation requires harsh conditions.…”