An Efficient and General Approach to β‐Functionalized Ketones.

Jiao, Jingliang; Nguyen, Larry X.; Patterson, Dennis R.; Flowers, Robert A.

doi:10.1002/chin.200733072

Cited by 2 publications

(3 citation statements)

References 7 publications

(9 reference statements)

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“…Cyclopropanation of 10 was achieved with ZnEt 2 /CH 2 I 2 . 13 The three-membered ring was then opened using CAN/NaI 14 to afford cycloheptenone 11. Saturation of C�C in 11, followed by regioselective enolization−silylation under the HMDS/TMSI/CH 2 Cl 2 15 conditions afforded 13 as expected.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Enantioselective Total Synthesis of 10-Desoxy Analogue of a Previously Reported Natural Peroxyguaidiol

Zha

2022

J. Org. Chem.

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Described herein is an enantioselective synthesis of an analogue of a previously reported guaiane endoperoxide isolated from aerial parts of Croton arboreous. The polycyclic framework of the target structure was constructed with the C-7 stereogenic center derived from L-(−)-carvone and other stereogenic centers installed via substrate chirality-induced asymmetric reactions, starting with the synthesis of the seven-membered ring through regioselective enolization of carvone, ring-expansion, and installation of a conjugated C�C bond. Further functionalization was then achieved through regioselective enolization, triflation, and installation of an isopropenyl group. During the synthesis, some exceptions to the well-known rules of "thermodynamic control" and "kinetic control" in enolization of asymmetric cyclic ketones were observed. In construction of the bridged five-membered and endoperoxy rings, a peroxycarbenium [3 + 2] cycloaddition reaction with alkenes was carried out with several alkenes-silyl-gemdihydroperoxides of different relative configurations. However, no expected [3 + 2] products were observed. Finally, the fivemembered ring was smoothly installed through an intramolecular Darzens reaction, and the peroxy functionality was introduced via a carbon-centered radical-mediated reaction with triplet oxygen, followed by an intramolecular etherification under acidic conditions. Comparison of the 1 H and 13 C NMR spectra of the synthetic analogue and the natural product revealed that the latter was definitely not an endoperoxide.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…(S)-5-Isopropyl-2-methylcyclohept-2-enone (14). To a solution of 12 (576 mg, 3.43 mmol) in dry CH 2 Cl 2 (20 mL) stirred at ambient temperature under N 2 (balloon) were added in sequence HN-(SiMe 3 ) 2 (HMDS, 1.4 ml, 6.8 mmol) and TMSI (0.7 mL, 5.1 mmol).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Enantioselective Total Synthesis of 10-Desoxy Analogue of a Previously Reported Natural Peroxyguaidiol

Zha

2022

J. Org. Chem.

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“…Under FeCl 3 conditions reported by Seagusa for cyclopropyl TMS ethers, 38 no reaction was observed. Use of ceric ammonium nitrate (CAN) with NaI, 46,47 which presumably generates iodine radicals, led to cleavage of the cyclopropane providing primary iodide 22, which proved to be highly unstable. This suggests that the ethyl ether is not being oxidized directly, but rather iodine radical is formed and attacks the least hindered carbon of the cyclopropane as proposed in Scheme 4.…”

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Pharmacophore-Directed Retrosynthesis Applied to Rameswaralide: Synthesis and Bioactivity of Sinularia Natural Product Tricyclic Cores

et al. 2019

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A Pharmacophore-Directed Retrosynthesis (PDR) strategy applied to rameswaralide provided simplified precursors bearing the common 5,5,6 (red) and 5,5,7 (blue) skeleton present in several cembranoid and norcembranoids from Sinularia soft corals. Key steps include a Diels-Alder lactonization organocascade delivering the common 5,5,6 core and a subsequent ring expansion affording a 5,5,7 core serviceable for the synthesis of rameswaralide. Initial structure-activity relationships of intermediates en route to the natural product has revealed interesting differential and selective cytotoxicity.

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An Efficient and General Approach to β‐Functionalized Ketones.

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 2 publications

References 7 publications

Enantioselective Total Synthesis of 10-Desoxy Analogue of a Previously Reported Natural Peroxyguaidiol

Enantioselective Total Synthesis of 10-Desoxy Analogue of a Previously Reported Natural Peroxyguaidiol

Pharmacophore-Directed Retrosynthesis Applied to Rameswaralide: Synthesis and Bioactivity of Sinularia Natural Product Tricyclic Cores

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