Kinetic studies of chloro-p-nitrophenylcarbene with acetone and diethyl fumarate

Reactivity patterns in the rhodium carbenoid induced tandem cyclization-cycloaddition reaction

“…We have also examined the rhodium acetate induced behavior of the keto analogue of diazo ester 4. When cis-l-(diazoacetyl)-2-benzoylcyclopentane (28) was exposed to the usual reaction conditions, cycloadduct 30 was formed cleanly and in high yield. This result clearly establishes o that the inefficiency of carbonyl ylide formation observed with diazo keto ester 4 is due to electronic differences in the trapping carbonyl group and is not related to any conformational cons taints imposed by the cyclic backbone.…”

“…Preparation and Rhodium(II) Acetate Catalyzed Reaction of cis-2-Benzoyl-l-(diazoacetyl)cyclopentane (28). A solution containing 1.03 g of cis-2-benzoylcyclopentanecarboxylic acid56 and 0.51 mL of methyl chloroformate in 30 mL of ether and 15 mL of tetrahydrofuran was treated with 0.92 mL of triethylamine.…”

“…The second material eluted from the column contained 0.17 g (15%) of a's-2-benzoyl-l-(diazoacetyl)cyclopentane (28): IR (neat) 2980, 2130,1680,1635,1450,1375, and 1225 cm"1; NMR (CDClg, 300 MHz) b 1.60-2.10 (m, 6 ), 3.01 (q, 1 H, J = 8.0 Hz), 4.01 (dt, 1 H, J = 7.7 and 7.0 Hz), 5.20 (s, 1 H), 7.33-7.48 (m, 3 H), and 7.82-7.85 (m, 2 H).…”

Heterocycles Derived from Heteroatom-Substituted Carbenes

“…The same diazo compound gave an acyclic compound 66 with acetone under the same conditions. The formation of these heterocycles can be explained by electrophilic attack of the silylcarbonylcarbenes on the carbonyl oxygen leading to the ketone ylide 67 . [1,5]-Cyclization followed by [3,3]-sigmatropic rearrangement of 67 then affords 60 or 64 .…”