Diverse sp3 C−H functionalization through alcohol β-sulfonyloxylation

Xu, Yan; Yan, Guobing; Ren, Zhi; Dong, Guangbin

doi:10.1038/nchem.2326

Cited by 103 publications

(63 citation statements)

References 46 publications

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“…147–169 There are several directing groups also capable of facilitating C(sp 3 )–H activation/carbon–halogen bond forming reactions. For example, Sahoo and co-workers reported methyl C(sp 3 )–H bromination and chlorination of α-quaternary aliphatic acid derivatives 145 with N -halophthalimides assisted by S -methyl- S -2-pyridyl-sulfoximine (Scheme 34).…”

Section: C(sp3)–h Activation Directed By Strongly Coordinating Auxmentioning

confidence: 99%

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

et al. 2016

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This Review summarizes the advancements in Pd-catalyzed C(sp3)–H activation via various redox manifolds, including Pd(0)/Pd(II), Pd(II)/Pd(IV), and Pd(II)/Pd(0). While few examples have been reported in the activation of alkane C–H bonds, many C(sp3)–H activation/C–C and C–heteroatom bond forming reactions have been developed by the use of directing group strategies to control regioselectivity and build structural patterns for synthetic chemistry. A number of mono- and bidentate ligands have also proven to be effective for accelerating C(sp3)–H activation directed by weakly coordinating auxiliaries, which provides great opportunities to control reactivity and selectivity (including enantioselectivity) in Pd-catalyzed C–H functionalization reactions.

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Section: C(sp3)–h Activation Directed By Strongly Coordinating Auxmentioning

confidence: 99%

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

et al. 2016

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“…The skeleton rearrangement of the O-menthyl oxime depicted in Scheme 7 [21,49] is also unusual. Intramolecular reaction between hydroxy and methyl groups in the substrates shown in Equations (23) and (24) was also mediated by the Pd(OAc) 2 /PhI(OAc) 2 system, giving cyclic ethers with four-to seven-membered rings. [51] The hydroxy group can be formed through in situ cleavage of a silyl ether under the reaction conditions, a process slightly improved by addition of a fluoride source [Equation (25)].…”

Section: Exo-palladationmentioning

confidence: 99%

C–O Bonds from Pd‐Catalyzed C(sp³)–H Reactions Mediated by Heteroatomic Groups

Bras

Мuzart

2018

Eur J Org Chem

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This review summarizes Pd‐catalyzed procedures leading to single C–O bonds from aliphatic C–H bonds of substrates bearing heteroatomic groups. Coordination of the latter to PdII species favors the activation of a C(sp3)–H bond and controls the regioselectivity, leading to a palladacycle as intermediate. Either PdII–Pd0 or PdII–PdIV redox catalytic cycles, possibly with a PdIII intermediate, might be involved, depending on the directing group and the oxidant.

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“…[4] Neufeldt and Sanford also recently reported the oxime-directed palladium-catalyzed dioxygenation of an adjacent alkene. [4] Neufeldt and Sanford also recently reported the oxime-directed palladium-catalyzed dioxygenation of an adjacent alkene.…”

mentioning

confidence: 98%

Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration

et al. 2015

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Chiral boronic esters are useful intermediates in asymmetric synthesis.W eh ave previously shown that carbonyl-directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters.W en ow report that the oxime-directed CAHB of alkyl-substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime-containing chiral tertiary boronic esters with yields up to 87 %a nd enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O-substituted hydroxylamines,t he generation of quaternary carbon stereocenters through carbon-carbon coupling reactions,a nd the preparation of chiral 3,4,4-trisubstituted isoxazolines.Catalytic asymmetric hydroboration (CAHB) has attracted renewed interest for the synthesis of chiral organoboronates. Many of the successful applications exploit the reaction of vinyl arene substrates. [1,2] Our research has instead focused on the directed CAHB of b,g-unsaturated amide and ester substrates.T he carbonyl moiety controls the regioselectivity of the rhodium-catalyzed addition of simple achiral boranes, such as pinacolborane (pinBH), and chiral phosphite and phosphoramidite ligands control the p-facial selectivity.A variety of chiral primary and secondary boronic esters are readily synthesized. [3] Fore xample,u nder the conditions specified in Scheme 1, methylidene derivative 1 undergoes regioselective CAHB on the alkene Si face to afford chiral hydroxyamide 2 with 96:4 e.r. after oxidation of the intermediate g-borylated amide.Encouraged by the success of carbonyl-directed CAHB, we are exploring the effectiveness of other potential directing groups.O xime functionality has been used in conjunction with av ariety of transition-metal catalyst systems to direct metalation reactions,m ost frequently to direct ortho-CÀH activation of aromatic substrates but increasingly for C(sp3)À Ha ctivation as well. [4] Neufeldt and Sanford also recently reported the oxime-directed palladium-catalyzed dioxygenation of an adjacent alkene. [5] Foro ur initial attempts at oxime-directed CAHB,w e employed benzophenone-derived allylic oxime ethers,such as 3.Whereas rhodium-catalyzed hydroboration of 3 led to some g-borylation, the yield of 4 (after oxidation) was low,and the enantioselectivity was poor.T he major side reactions are ortho-borylation of the benzophenone-derived oxime with concomitant alkene reduction. [6] We now report that the corresponding acetone-derived oxime ethers are excellent substrates for oxime-directed CAHB;for example, 5a underwent oxime-directed CAHB/oxidation to give 6a in good yield (71 %) and with high levels of asymmetric induction (95:5 e.r.). Furthermore,t he borylated intermediate is at ertiary boronic ester arising from Re-face b-borylation;i n contrast, carbonyl-directed CAHB of 1 proceeds by Si-face gborylation. It seems likely that the contrasting regio-and stereochemical outcomes observed with 1 versus 5aare...

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Diverse sp3 C−H functionalization through alcohol β-sulfonyloxylation

Cited by 103 publications

References 46 publications

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

C–O Bonds from Pd‐Catalyzed C(sp³)–H Reactions Mediated by Heteroatomic Groups

Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration

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Diverse sp3 C−H functionalization through alcohol β-sulfonyloxylation

Cited by 103 publications

References 46 publications

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

Palladium-Catalyzed Transformations of Alkyl C–H Bonds

C–O Bonds from Pd‐Catalyzed C(sp3)–H Reactions Mediated by Heteroatomic Groups

Synthesis of Chiral Tertiary Boronic Esters by Oxime‐Directed Catalytic Asymmetric Hydroboration

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C–O Bonds from Pd‐Catalyzed C(sp³)–H Reactions Mediated by Heteroatomic Groups