Catalytic reductive ring opening of epoxides enabled by zirconocene and photoredox catalysis

Aida, Kazuhiro; Hirao, Marina; Funabashi, Aiko; Sugimura, Natsuhiko; Ota, Eisuke; Yamaguchi, Junichiro

doi:10.1016/j.chempr.2022.04.010

Cited by 30 publications

(24 citation statements)

References 74 publications

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“…The transformation was also examined in single-phase organic solvents by using varying amounts of bases (Et 3 N/NaH) . The reaction in the absence of any additives (Table , entry 1) resulted in 2a as the major product.…”

Section: Resultsmentioning

confidence: 99%

“…Previous literature has reported the exclusive reactivity of the NH group in either basic, − Lewis-acidic, or neat conditions to form the N -Boc derivative of prolinol ( 2a ). Base-solvent combinations such as NaOH–THF, NaOH–THF:H 2 O, NaOH–dioxane:H 2 O, aq NaOH−DCM, KOH−THF, Na 2 CO 3 –NaOH–dioxane, NaHCO 3 –THF:H 2 O, Et 3 N–MeOH, and Et 3 N–DCM , have been used for the selective N -Boc protection of prolinol. Selectivity toward N -Boc protection of 2-aminophenol has also been reported using ZnCl 2 as Lewis acid in CH 3 CN:H 2 O media .…”

Section: Introductionmentioning

confidence: 99%

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Concept-Driven Chemoselective O/N-Derivatization of Prolinol: A Bee-Line Approach to Access Organocatalysts

et al. 2023

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An investigation into the sensitivity of reaction conditions to a highly utilized protocol has been reported, wherein the mono-Boc functionalization of prolinol could be controlled for the exclusive synthesis of either N-Boc, O-Boc, or oxazolidinone derivatives. Mechanistic investigation revealed that the elementary steps could possibly be controlled by (a) a requisite base to recognize the differently acidic sites (NH and OH) for the formation of the conjugate base, which reacts with the electrophile, and (b) the difference in nucleophilicity of the conjugate basic sites. Herein, a successful chemoselective functionalization of the nucleophilic sites of prolinol by employing a suitable base is reported. This has been achieved by exploiting the relative acidity difference of NH and OH along with the reversed nucleophilicity of the corresponding conjugate bases N– and O–. This protocol has also been used for the synthesis of several O-functionalized prolinol derived organocatalysts, few of which have been newly reported.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Concept-Driven Chemoselective O/N-Derivatization of Prolinol: A Bee-Line Approach to Access Organocatalysts

et al. 2023

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“…In our recent study, we reported a visible light-mediated ring opening of epoxides with zirconocene to provide the more-substituted alcohol regioisomer, which represents the opposite regioselectivity to titanocene-catalyzed reactions (Figure 2A). 28 The stronger Zr−O bond, compared to the Ti−O bond, renders the ring opening of epoxides more exergonic, influencing the regiochemical outcome.…”

Section: ■ Introductionmentioning

confidence: 99%

Chlorine Atom Transfer of Unactivated Alkyl Chlorides Enabled by Zirconocene and Photoredox Catalysis

Okita

Aida

Tanaka

et al. 2023

Precision Chemistry

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Alkyl chlorides are robust precursors to carbon radicals; however, their relative inertness has hampered their practical use. Although modern photochemical strategies have greatly enhanced the utility of alkyl chlorides as radical precursors, these methods often depend on strongly reducing conditions leading to unproductive side reactions. Here, we report a catalytic radical generation from 1°, 2°, and 3°unactivated alkyl chlorides with zirconocene and photoredox catalysis, which enables both hydrogenation and borylation on a range of structurally complex molecules. This mild zirconocene-catalyzed protocol shows that zirconium can render the C−Cl bond cleavage more exergonic and can lower the activation energy of the transition state, amplifying the ability of metallocenes toward halogen atom transfer.

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“…Being highly strained molecules, epoxides are susceptible to ring opening by nucleophiles to get rid of angle strain. 6 Previously, the regiodivergent hydroborative ring-opening of epoxides with selective C-O bond activation, 7 nickel-catalyzed regiodivergent opening of epoxides with aryl halides, 8 and zirconocene and photoredox catalyzed ring opening of epoxides 9 have been reported. Furthermore, various catalytic ring openings of an epoxide to aldehyde (Meinwald rearrangement) have also been established (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Continuous-flow Fe-zeolite-catalyzed temperature-directed synthesis of bioactive tetraketones and xanthenes using epoxides and cyclic-1,3-diketones via a Meinwald rearrangement

Mondal¹,

Pandey²,

Gnanaprakasam³

2023

React. Chem. Eng.

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Catalytic reductive ring opening of epoxides enabled by zirconocene and photoredox catalysis

Cited by 30 publications

References 74 publications

Concept-Driven Chemoselective O/N-Derivatization of Prolinol: A Bee-Line Approach to Access Organocatalysts

Concept-Driven Chemoselective O/N-Derivatization of Prolinol: A Bee-Line Approach to Access Organocatalysts

Chlorine Atom Transfer of Unactivated Alkyl Chlorides Enabled by Zirconocene and Photoredox Catalysis

Continuous-flow Fe-zeolite-catalyzed temperature-directed synthesis of bioactive tetraketones and xanthenes using epoxides and cyclic-1,3-diketones via a Meinwald rearrangement

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