Untitled

López-Ruíz, Heraclio; Zard, Samir Z.

doi:10.1039/b109637k

Cited by 37 publications

(24 citation statements)

References 13 publications

(5 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This constraint is seldom obeyed in the case of additions to vinyl pinacolato boronate 14 as the corresponding adduct radical 15 is stabilized by delocalization into the empty orbital on the boron atom, and this radical is in many cases more stable than initial radical 8 . Indeed, additions to vinylBpin ( 14 ) are capricious and often low‐yielding . In contrast, radicals 17 from addition to vinylB(MIDA) ( 16 ) cannot benefit from such stabilization and are in general less stable than initial radical 8 .…”

Section: Resultsmentioning

confidence: 99%

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

2019

Self Cite

View full text Add to dashboard Cite

Pinacolato boronates (Bpin) with an empty p‐orbital on boron stabilize an adjacent carbon radical, in contrast to diethanolamino boronates [B(DEA)] where the boron is sp3‐hybridized. By alternately placing a pinacol or diethanolamine moiety on the boron atom, thus stabilizing or not stabilizing the corresponding adjacent radical, it is possible to control the behavior of α‐boronyl xanthates and construct a large variety of terminal or internal boronates in a modular fashion. The remarkable tolerance of polar groups and the ability to introduce quaternary centers are particularly noteworthy features of this process.

show abstract

Section: Resultsmentioning

confidence: 99%

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Zard group recognized this challenge and addressed it by tuning the boron ligand set (Scheme ) . In two previous reports, the authors found that the radical addition reaction of xanthates and alkenylB(pin) reagents was inefficient relative to the reaction with other alkenes . The authors attributed the poor overall reactivity to the intermediacy of stabilized radical 3 (L 2 = pin).…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Radical Addition to Alkenylboron Compounds

Lovinger

Morken

2019

Eur J Org Chem

View full text Add to dashboard Cite

The addition of carbon-centered radicals to alkenylboron compounds provides a useful method for the construction of organoboron reagents which are versatile reagents in chemical synthesis. While the first examples of this type or process appeared 70 years ago, until recently, attention to this type [a] G. Scheme 7. Aggarwal′s photoredox-catalyzed radical addition of carboxylic acids to alkenylboron reagents. Conditions: RCO 2 H, 1 % Ir catayst, 1.1 equiv. Cs 2 CO 3 , DMF, 35°C, 40 W blue LED.reductant furnishes an Fe-H species that undergoes H atom transfer; subsequent conjugate addition of the α-boryl radical to an activated alkene allowed C-C bond formation with a second reactant (Scheme 8). Interestingly, the reaction operates smoothly with both three-coordinate alkenylB(pin) derivatives as well as four-coordinate alkenylB(mida) compounds. According to the proposed mechanism, it is plausible that the two types of alkenylboron compounds react by different paths, with the non-stabilized α-boryl radical (8, BL 2 = mida) reacting as shown in Scheme 8, but the stabilized radical (8, L 2 = pin) undergoing reduction to an α-boryl carbanion prior to engaging in direct conjugate addition to give 10. [20] Scheme 8. Baran′s hydrogen-atom-transfer/radical conjugate addition involving alkenylboron compounds.Our group has studied whether stabilized α-boryl radical intermediates, generated by addition of electron-rich radicals to vinylB(pin), might be intercepted with chiral nickel complexes Eur.

show abstract

“…Strong polar effects favor an efficient and selective iodine-atom transfer over oligomerization. [43][44][45] a-Haloboronic esters have been used in tin-mediated (Scheme 1A) [46][47][48][49] and metal-catalyzed radical processes. Based on these simple considerations,itisexpected that iodine-atom transfer between 1-iodoalkylboronic esters and alkenes should be possible,b ut still challenging,d ue to moderate thermodynamic and polar effects.…”

mentioning

confidence: 99%

“…[50][51][52] Chen and co-workers have reported Pd 0 -catalyzed cyclopropanation of norbornene using potassium iodomethyltrifluoroborate. [43,44,46,[57][58][59][60][61] and to ate complexes of vinylboronates. Radical stabilization energies (RSEs) of 1-borylated radicals and resonanceh ybrids of boronic esters derived radicals.…”

mentioning

confidence: 99%

“…[42] Recently,Z ard and co-workers rationalized the inefficiencyo ft he xanthate-transfer-mediated addition of electrophilic radicals to pinacol vinylboronate by al ack of favorable thermodynamic and polar effects. [43][44][45] a-Haloboronic esters have been used in tin-mediated (Scheme 1A) [46][47][48][49] and metal-catalyzed radical processes. [50][51][52] Chen and co-workers have reported Pd 0 -catalyzed cyclopropanation of norbornene using potassium iodomethyltrifluoroborate.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Cyclopropanation of Terminal Alkenes through Sequential Atom‐Transfer Radical Addition/1,3‐Elimination

et al. 2019

View full text Add to dashboard Cite

An operationally simple method to affect an atomtransfer radical addition of commercially available ICH 2 Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in ao ne-pot process into the corresponding cyclopropane upon treatment with af luoride source.T his method is highly selective for the cyclopropanation of unactivated terminal alkenes over non-terminal alkenes and electron-deficient alkenes.D ue to the mildness of the procedure,awide range of functional groups such as esters, amides,a lcohols,k etones,a nd vinylic cyclopropanes are well tolerated.

show abstract

Untitled

Abstract: The radical addition of various xanthates to allyl or vinyl boronates occurs smoothly in the presence of a small amount of lauroyl peroxide as initiator to give good yields of usefully functionalised boronates.

Cited by 37 publications

References 13 publications

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

Recent Advances in Radical Addition to Alkenylboron Compounds

Cyclopropanation of Terminal Alkenes through Sequential Atom‐Transfer Radical Addition/1,3‐Elimination

Contact Info

Product

Resources

About