Organic & Biomolecular Chemistry, Год журнала: 2019, Номер 18(4), С. 618 - 637
Опубликована: Дек. 3, 2019
A variety of catalytic asymmetric reactions have been realized during the past decade through combined action palladium and chiral phosphoric acids (CPAs). This review surveys key examples examines underlying mechanisms stereoinduction.
Язык: Английский
Organic Letters, Год журнала: 2025, Номер unknown
Опубликована: Март 17, 2025
Ketyl radical-mediated ring opening and [2σ+2π] cycloaddition of cyclopropyl ketones (CPKs) with alkynes typically require activation by alkyl, aryl, or carbonyl groups yielding cyclopentenes having one two non-adjacent stereocenters. We developed a one-pot multicomponent reaction diboryl-activated CPKs aldehydes that merges ketyl radical chemistry allylboration. This method enabled highly diastereoselective access to densely functionalized featuring homoallylic alcohol, ketone, alkenyl boronate motifs on adjacent quaternary, tertiary, secondary stereogenic centers. Additionally, diboryl also allowed the synthesis rare ketone-functionalized γ,γ-disubstituted allylic diborons.
Язык: Английский
Процитировано
2
ACS Catalysis, Год журнала: 2020, Номер 10(10), С. 5793 - 5804
Опубликована: Апрель 13, 2020
The positional isomerization of alkenes is a well-known process mediated by various transition metal complexes. Nevertheless, systems which isomerize with complete regio- and stereoselectivity are rare. Most reported cases proceed through 1,3-hydrogen shift (allyl) mechanisms, rather than the generally more common 1,2-hydride (alkyl) mechanism, provoking consideration unique opportunities former mechanism offers. Accordingly, first part this Perspective article will cover stereoselective alkene operating an emphasis on origin stereocontrol. Next, examples where these employed in tandem subsequent transformations to rapidly form complex molecular architecture be discussed, illustrating potential as strategic tool synthesis.
Язык: Английский
Процитировано
120
Journal of the American Chemical Society, Год журнала: 2017, Номер 139(31), С. 10903 - 10908
Опубликована: Июль 14, 2017
A cationic ruthenium(II) complex catalyzes double-bond transposition of 1,1-di(boryl)alk-3-enes to generate in situ 1,1-di(boryl)alk-2-enes, which then undergo chiral phosphoric acid catalyzed allylation aldehydes producing homoallylic alcohols with a (Z)-vinylboronate moiety. 1,2-Anti stereochemistry is installed an enantioselective manner. The (Z)-geometry forged the products allows their isolation form 1,2-oxaborinan-3-enes, upon further synthetic transformations are operated.
Язык: Английский
Процитировано
96
Angewandte Chemie International Edition, Год журнала: 2018, Номер 57(39), С. 12930 - 12934
Опубликована: Июль 2, 2018
We report the successful generation of (diborylmethyl)zinc(II) species by transmetallation beteween isolable (diborylmethyl)lithium and zinc(II) halide (X=Br, Cl) their application in synthesis enantioenriched gem-diborylalkanes bearing a stereogenic center at β-position diboryl groups an asymmetric allylic substitution reaction. The reaction has broad substrate scope, various can be obtained good yields with excellent enantioselectivity. Further elaboration provides access to diverse set valuable chiral building blocks.
Язык: Английский
Процитировано
96
Journal of the American Chemical Society, Год журнала: 2017, Номер 139(40), С. 14061 - 14064
Опубликована: Сен. 22, 2017
A copper-catalyzed three-component linchpin coupling method for the stereoselective union of readily available epoxides and allyl electrophiles is disclosed. Transformations employ [B(pin)]2-methane as a conjunctive reagent, resulting in formation two C–C bonds at single carbon center bearing C(sp3) organoboron functional group. Products are obtained 42–99% yield, up to >20:1 dr. The utility approach highlighted by stereospecific transformations entailing allylation, tandem cross coupling, application synthesis 1,3-polyol motifs.
Язык: Английский
Процитировано
92
Accounts of Chemical Research, Год журнала: 2021, Номер 54(20), С. 3917 - 3929
Опубликована: Окт. 6, 2021
ConspectusChemo- and stereoselective transformations of polyborylalkanes are powerful efficient methods to access optically active molecules with greater complexity diversity through programmed synthetic design. Among the various polyborylalkanes, gem-diborylalkanes have attracted much attention in organic chemistry as versatile handles. The notable advantage lies their ability generate two key intermediates, α-borylalkyl anions (gem-diborylalkyl) anions. These different intermediates can be applied enantioselective reactions rapidly a diverse set enantioenriched organoboron compounds, which further manipulated chiral molecule libraries via stereospecific C(sp3)–B bond transformations.In this Account, we summarize our recent contributions development catalytic chemo- using nucleophiles, categorized follows: (1) copper-catalyzed coupling electrophiles (2) design synthesis (diborylmethyl)metallic species applications reactions. Since Shibata Endo reported Pd-catalyzed chemoselective Suzuki–Miyaura cross-coupling organohalides 2014, Morken Hall subsequently developed first analogous TADDOL-derived phosphoramidite supporting ligand palladium catalyst. This discovery sparked interest electrophiles. Our initial studies focused on generating (α-borylmethyl)copper by enantiotopic-group-selective transmetalation copper complexes aldimines ketimines afford syn-β-aminoboronate esters excellent enantio- diastereoselectivity. Moreover, allylation that proceeded reaction situ-generated (α-borylalkyl)copper allyl bromides. Mechanistic investigations revealed between complex occurred open transition state rather than closed state, thereby effectively species. We also utilized such (diborylmethyl)silanes (diborylmethyl)zinc halides succeeded developing aryl iodides benzylic 1,1-silylboronate esters, could used for consecutive molecules. In addition, synthesized time isolated (diborylmethyl)lithium zinc(II) utilization bearing center at β-position an iridium-catalyzed allylic substitution process. addition research efforts, include other groups. hope Account will draw community gem-diboryl compounds provide guiding principles future compounds.
Язык: Английский
Процитировано
91
Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(28), С. 9448 - 9452
Опубликована: Май 6, 2019
A series of in situ formed alkenyl diboronate complexes from Grignard reagents (commercially available or prepared bromides and Mg) with B2 Pin2 (bis(pinacolato)diboron) react diverse alkyl halides by a Ru photocatalyst to give various gem-bis(boryl)alkanes. Alkyl radicals add efficiently the complexes, adduct radical anions undergo radical-polar crossover, specifically, 1,2-boryl-anion shift boron α-carbon sp2 center. This transformation shows good functional-group compatibility can serve as powerful synthetic tool for late-stage functionalization complex compounds. Measurements quantum yield reveal that radical-chain mechanism is operative which diboronates acts reductive quencher excited state photocatalyst.
Язык: Английский
Процитировано
88
ACS Catalysis, Год журнала: 2021, Номер 11(16), С. 10660 - 10680
Опубликована: Авг. 12, 2021
Recent years have witnessed an increase in the popularity of α-boryl organometallic reagents as versatile nucleophiles asymmetric synthesis. These compounds been adopted chemo- and stereoselective coupling reactions with a number different electrophiles. The resulting enantioenriched boronic esters can be applied stereospecific carbon-carbon or carbon-heteroatom bond construction reactions, enabling two-step strategy for complex structures high efficiency functional group compatibility. Due to these reasons, tremendous effort has devoted preparation enantiomerically enriched development related racemic prochiral materials. In this review, we describe enantio- diastereoselective that involve starting materials products showcase their synthetic utility.
Язык: Английский
Процитировано
65
Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(18)
Опубликована: Март 6, 2024
Geminal bis(boronates) are versatile synthetic building blocks in organic chemistry. The fact that they predominantly serve as nucleophiles the previous reports, however, has restrained their potential. Herein we disclose ambiphilic reactivity of α-halogenated geminal bis(boronates), which first catalytic utilization was accomplished by merging a formal Heck cross-coupling with highly diastereoselective allylboration aldehydes or imines, providing new avenue for rapid assembly polyfunctionalized boron-containing compounds. We demonstrated this cascade reaction is efficient and compatible various functional groups, wide range heterocycles. In contrast to classical Pd(0/II) scenario, mechanistic experiments DFT calculations have provided strong evidence cycle involving Pd(I)/diboryl carbon radical intermediates.
Язык: Английский
Процитировано
14
Organic Letters, Год журнала: 2017, Номер 19(15), С. 4054 - 4057
Опубликована: Июль 19, 2017
We report a highly chemo- and stereoselective crotylation of aldehydes cyclic aldimines with allylic-gem-diboronate ester as new type organoboron reagent. The undergoes the in excellent stereoselectivity, forming anti-5,6-disubstituted oxaborinin-2-ols or (E)-δ-boryl-anti-homoallylic amines high efficiency. reaction shows wide range substrate scope functional group tolerance. synthetic applications obtained products, including stereospecific C–C, C–O, C–Cl bond formation, are also demonstrated.
Язык: Английский
Процитировано
73