Reactions of Ethyl Diazoacetate with Aromatic Compounds Containing Hetero Atoms Attached to the Benzyl Carbon

Asymmetric C–H insertion of Rh(II) stabilized carbenoids into acetals: A C–H activation protocol as a Claisen condensation equivalent

“…Compound 16 could be identified unambiguously from its gs-HMBC and gs-HSQC NMR spectra as well as from comparison to published NMR data [38]. The formation of 16 can be rationalized by the intermediate formation of an oxonium ylide formed from the carbenoid with one oxygen atom of the dioxolane ring followed by a [1,2] Stevens-type rearrangement [39,40]. The formation of 16 with 47% ee is noteworthy and suggests that during the ylide formation/rearrangement, the chiral catalyst is not dissociated completely from the ylide and therefore is still able to influence the stereochemical outcome of the rearrangement.…”

Oxonium Ylides Generated from 1,4‐Disubstituted α‐Diazo Glutaconimides: a Rich Source of Diverse Oxygen Heterocyclic Frameworks

“…White powder; mp 186-187°C. 1 5, 163.3, 159.0, 136.2, 134.2, 129.5, 129.3, 129.1, 128.9, 128.4, 128.4, 120.6, 79.2, 72.4, 70.9, 65.7, 43.4 10,dodec-1( 12)-ene-9,11-dione ( 12 1, 139.1, 137.1, 134.9, 134.2, 130.1, 129.3, 129.0, 128.8, 128.3, 128.1, 74.4, 70.6, 68.0, 48.0, 36.6 Yield: 22 mg (46 %). White powder; mp 123-125°C.…”

“…In 2019, we reported [8] the first example of an alternative evolution course for oxonium ylide 1 b generated from a cyclic diazo compound (α-diazo homophthalimide 4 [9] ) -the Stevens-type formal [1,2]migration of an alkyl group (likely also mediated by participation of a solvent molecule) resulting in the formation of a ringexpanded spirocyclic framework. In contrast, Stevens-type ring expansions of cyclic ethers using carbenes generated from acyclic α-diazocarbonyl compounds had been known since the pioneering publication of Gutsche [10] and had been illustrated by a wealth of examples in the literature. [11] In 2020, the Stevens-type spirocyclization with tetrahydrofuran was extended to another type of heterocyclic α-diazocarbonyl compounds -namely, (E)-3-arylidene-4-diazopyrrolidine-2,5-diones 5 [12] (Scheme 1).…”

Synthetic Applications of Carbonyl Ylides Generated via the Tandem Cyclization Cycloaddition Reaction of Rhodium Carbenoids

“…This reactive species then undergoes proton loss to produce 22 in 58% yield. 29 These proton transfer reactions were found to proceed with high regiospccificity." 31 Intramolecular attack of a rnetallo-carbenoid onto an adjacent carbonyl oxygen produces a carbonyl ylide in a fivemembered ring which undergoes a subsequent proton transfer to afford the 3-furanone system.…”