Catalytic Enantioselective [3 + 2]-Cycloadditions of Diazoketone-Derived Aryl-Substituted Carbonyl Ylides

Abstract

An evaluation of alpha-aryl-alpha-diazodiones in tandem carbonyl ylide formation-enantioselective [3 + 2]-cycloaddition reactions is described. Such substrates were designed to allow investigation of the electronic characteristics of the dipole upon asymmetric induction. Intramolecular cycloadditions (with a tethered alkene dipolarophile) were found to occur in good to quantitative yields, with a difference in ee exhibited by the two electronically different diazodiones 8 and 9. Intermolecular cycloadditions using diazodiones 12 and 13 with DMAD and arylacetylenes 16-18 again demonstrated that electronics play a key role in determining the outcome of the cycloaddition reactions. Enantioselectivities of up to 76% were observed.

Oxapolycycles from One‐Pot Cross‐Metathesis/Carbonyl Ylide Formation‐Intramolecular Cycloaddition of α‐Diazo‐β‐keto Esters

“…[13] Aryl-substituted dipolarophiles underwent efficient cycloaddition with no observable influence of the electronic nature of the aromatic ring being evident (entries [5][6][7][8][9][10][11][12]. [14] Trisubstituted olefins 11m and n gave the corresponding cycloadducts 13m and n efficiently (74 % and 77 % yields, respectively). Table 1.…”

Chemoselective Two-Directional Reaction of Bifunctionalized Substrates: Formal Ketal-Selective Mukaiyama Aldol Type Reaction

“…1, 34.9, 48.9, 97.1, 126.5, 127.3, 128.8, 131.5, 132.7, 141.1, 197.7; MS (ESI-TOF) m/z 229 [ Found: C, 64.76; H, 9.00. γ,γ-Dimethoxy carbonyl compounds 1c-1j were prepared by modification of reported procedure as follows. 6 γ,γ-Diethoxy derivative 1k was also prepared in a similar manner by using HC(OEt) 3 and EtOH as reagents for the first step.…”

“…To a solution of N,4,4-trimethoxy-N-methylpentanamide 6 (1.03 g, 4.98 mmol) in THF (20 mL), a 3.0 M solution of MeMgBr in Et 2 O (3.3 mL, 9.9 mmol) was added over 15 min at 0 °C. After being stirred for 1 h at the same temperature, the reaction mixture was acidified by a saturated NH 4 Cl aqueous solution (30 mL), then it was extracted with Et 2 O (30 mL x 3).…”

Rhodium(II)‐Catalyzed 1,3‐Dipolar Cycloaddition Reactions

“…Hodgson [104] applied chiral induction in an intramolecular cycloaddition of a carbonyl ylide using Davies' [105] chiral N-arylsulfonyl prolinate rhodium(II) catalyst 24. Other chiral catalysts were later applied to this [106,107] and other systems [101,[108][109][110][111], with enantioselectivities of up to 92% being achieved. Hashimoto developed the N-phthaloyl-(S)amino acid-based chiral dirhodium catalysts 28 and 29, which have been successfully used in the enantioselective 1,3-dipolar cycloaddition of carbonyl ylides to obtain enantioselectivities of up to 93% [112,113].…”