Enantioselective Conjunctive Cross-Coupling of Bis(alkenyl)borates: A General Synthesis of Chiral Allylboron Reagents

Journal of the American Chemical Society, Journal Year: 2017, Volume and Issue: 139(14), P. 5027 - 5030

Published: March 25, 2017

Palladium-catalyzed conjunctive cross-coupling is used for the synthesis of enantioenriched allylboron reagents. This reaction employs nonsymmetric bis(alkenyl)borates as substrates and appears to occur by a mechanism that involves selective activation less substituted alkene followed migration more during course Pd-induced metalate rearrangement.

Language: Английский

---

Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols Using Palladium and a Chiral Phosphoric Acid

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(24), P. 6989 - 6993

Published: May 10, 2017

Abstract ( E )‐δ‐Boryl‐substituted anti ‐homoallylic alcohols are synthesized in a highly diastereo‐ and enantioselective manner from 1,1‐di(boryl)alk‐3‐enes aldehydes. Mechanistically, the reaction consists of 1) palladium‐catalyzed double‐bond transposition to 1,1‐di(boryl)alk‐2‐enes, 2) chiral phosphoric acid catalyzed allylation aldehydes, 3) geometrical isomerization Z isomer. As result, configurations two centers one double bond all controlled with high selectivity single vessel.

Language: Английский

---

Enantioselective Synthesis of anti-1,2-Oxaborinan-3-enes from Aldehydes and 1,1-Di(boryl)alk-3-enes Using Ruthenium and Chiral Phosphoric Acid Catalysts

Journal of the American Chemical Society, Journal Year: 2017, Volume and Issue: 139(31), P. 10903 - 10908

Published: July 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.

Language: Английский

---

Copper-Mediated S_N2′ Allyl–Alkyl and Allyl–Boryl Couplings of Vinyl Cyclic Carbonates

Organic Letters, Journal Year: 2017, Volume and Issue: 19(22), P. 6096 - 6099

Published: Oct. 27, 2017

A method for the copper-catalyzed borylmethylation and borylation of vinyl cyclic carbonates through an SN2' mechanism is reported. These singular reactions involve selective allylic substitutions with concomitant ring opening carbonate extrusion CO2 formation a useful hydroxyl functionality in single step. The stereoselectivity homoallylic processes can be controlled, synthetically unsaturated (E)-pent-2-ene-1,5-diols (E)-but-2-ene-1,4-diols are accessed.

Language: Английский

---

Catalytic Chemo- and Enantioselective Transformations of gem-Diborylalkanes and (Diborylmethyl)metallic Species

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(20), P. 3917 - 3929

Published: Oct. 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.

Language: Английский

---

A Regio‐ and Stereodivergent Synthesis of Homoallylic Amines by a One‐Pot Cooperative‐Catalysis‐Based Allylic Alkylation/Hofmann Rearrangement Strategy

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(31), P. 10521 - 10527

Published: May 27, 2019

Abstract Herein, we report a modular synthetic route to linear and branched homoallylic amines that operates through sequential one‐pot Lewis base/transition‐metal catalyzed allylic alkylation/Hofmann rearrangement strategy. This protocol is operationally trivial, proceeds from simple easily prepared substrates catalysts, enables all aspects of regio‐ stereoselectivity be controlled conserved experimental protocol. Overall, the high levels enantio‐, regio‐, diastereoselectivity obtained, in concert with ability access orthogonally protected or free amines, render this straightforward effective approach for preparation useful enantioenriched amines. We have also demonstrated utility products context pharmaceutical synthesis.

Language: Английский

---

Copper-Catalyzed Enantiotopic-Group-Selective Allylation of gem-Diborylalkanes

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(2), P. 1069 - 1077

Published: Jan. 4, 2021

We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination copper(I) bromide and H8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system provide various enantioenriched homoallylic boronate esters, containing boron-substituted stereogenic center that is solely from gem-diborylalkanes, in good yields high enantiomeric ratios under mild conditions. Experimental theoretical studies have been conducted elucidate reaction mechanism, revealing how transmetalation chiral copper complex occurs generate α-borylalkyl-copper species for first time. Additional synthetic applications synthesis building blocks are also included.

Language: Английский

---

Pd/IPr^BIDEA-Catalyzed Hydrodefluorination of gem-Difluorocyclopropanes: Regioselective Synthesis of Terminal Fluoroalkenes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 146(1), P. 24 - 32

Published: Oct. 13, 2023

Developing new strategies to enable chemo- and regioselective reductions is an important topic in chemical research. Herein, efficient Pd/IPr

Language: Английский

---

Facile Access to Cyclopropylboronates via Stereospecific Deborylative Cyclization: A Leaving Group‐Assisted Activation of Geminal Diborons

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(21)

Published: March 24, 2023

Herein we reported a transition metal-free deborylative cyclization strategy, based on which two routes have been developed, generating racemic and enantioenriched cyclopropylboronates. The of geminal-bis(boronates) bearing leaving group was highly diastereoselective, tolerating few functional groups applicable to heterocycles. When optically active epoxides were used as the starting materials, cyclopropylboronates could be efficiently prepared with >99 % stereospecificity. Mechanistic studies showed that at γ-position played crucial role significantly promoted activation gem-diboron moiety.

Language: Английский

---

Ir‐Catalyzed Enantioselective Synthesis of gem‐Diborylalkenes Enabled by 1,2‐Boron Shift

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(32)

Published: June 15, 2023

Abstract Asymmetric cross‐couplings based on 1,2‐carbon migration from B‐ate complexes have been developed efficiently to access valuable organoboronates. However, enantioselective reactions triggered by 1,2‐boron shift remained be unaddressed synthetic challenge. Here, Ir‐catalyzed asymmetric allylic alkylation enabled was developed. In this reaction, we disclosed that excellent enantioselectivities were achieved through an interesting dynamic kinetic resolution (DKR) process of carbonates at the elevated temperature. Notably, highly (bis‐boryl)alkenes array diversifications versatile molecules. Extensive experimental and computational studies conducted elucidate reaction mechanism DKR clarify origin enantioselectivities.

Language: Английский

---