Reaction of carbonyl compounds with ethyl lithiodiazoacetate. Studies dealing with the rhodium(II)-catalyzed behavior of the resulting adducts

Abstract

shown by GLC analysis and 13C NMR to contain 5a (lo%), unknown compounds (12%), and 3a (78%). The data (GLC and '3c NMR) are identical with those from the products from reaction of 1 with methanol a t room temperature. Acknowledgment. We acknowledge grants from the Research Committee of the New Zealand Universities J. Org. Chem. 1990,55, 4144-4153 Grants Committee and helpful discussions with Professor M. A. Battiste.Supplementary Material Available: 13C and 'H NMR spectra for compounds 1,3a-d, 5a,b, 6a,b, 12,14a-c, 16a,b, and 18a,b (26 pages). Ordering information is given on any current masthead page.The carbenoid intermediate derived by treating ethyl 2-diazo-4-phthalimidobutyrate with rhodium(I1) octanoate undergoes transannular cyclization onto the adjacent imido carbonyl group. The resulting cyclic carbonyl ylide dipole was trapped with several dipolarophiles. In an attempt to prepare related substrates for cyclization studies, the reaction of ethyl lithiodiazoacetate with various aldehydes and ketones was studied. Treatment of the a-diazo-0-hydroxy ester derived from acetone or cyclopentanone with rhodium(I1) octanoate gave rise to a 0-keto ester. The exclusive phenyl shift encountered with acetophenone is in keeping with migration to an electron-deficient center. The reaction works well with acrolein, leading to high yields of 3-oxo-4-pentenoate. The 1,2-hydrogen shift pathway was found to proceed much faster than intramolecular cyclopropanation. Dehydration of the a-diazo-@-hydroxy esters generates vinyl diazo esters, which readily cyclize to lH-pyrazoles on thermolysis.

Development of Dirhodium(II)-Catalyzed Generation and Enantioselective 1,3-Dipolar Cycloaddition of Carbonyl Ylides

“…[34a] Applying the optimised catalyst ± solvent combination for intermolecular cycloaddition of a-diazoketones with DMAD reported by Hashimoto [34a] (catalyst 24, PhCF 3 as solvent) to 2-diazo-3,6-diketoester 2 c at 25 8C resulted in only essentially racemic cycloadduct 3 c (90 % yield, 1 % ee). Furthermore, cycloadduct 25 (R 1 CO 2 Et, R 2 Me) [35] was obtained in only 33 % ee under the same conditions in the reaction of 2-diazo-3,6-diketoester 23 (R 1 CO 2 Et, R 2 Me) [35] with DMAD [a-diazoketone 23 (R 1 H, R 2 Me) gave cycloadduct in 80 % ee]. [34a] These last results indicate that ee is rather sensitive to variation in the electronic structure of the dipole.…”

Studies on diastereoselective reduction of cyclic β-ketoesters with boron hydrides. Part 4: The reductive profile of functionalized cyclohexanone derivatives

“…The spectroscopic data of this compound, which was obtained in 71% yield, are in agreement with that previously related in literature. 38,39 4.4.3. 2-Carboisobutoxycyclohexanone (3c).…”

Chemical Synthesis of the ODM-201’s Diastereomers through an Efficient Intramolecular 1,3-Dipolar Cycloaddition

“…9) The following dehydration of β-hydroxy diazo carbonyl compounds (5a, b) was quite challenging considering the relative labile character of diazo group. We systematically screened several conditions including the common dehydration condition i.e., excessive phosphorus oxychloride in pyridine, 10) which failed to provide a desirable yield. Finally, we found that when the combination of (CF 3 CO) 2 O and Et 3 N in CH 2 Cl 2 was employed, the vinyl diazo carbonyl compounds (6a, b) were obtained in 84-90% yield.…”