1,2-Boryl Migration Empowers Regiodivergent Synthesis of Borylated Furans

Shiroodi, Roohollah Kazem; Koleda, Olesja; Gevorgyan, Vladimir

doi:10.1021/ja507054j

Cited by 93 publications

(56 citation statements)

References 48 publications

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“…[10] Remarkably,r ecent advances from the groups of Perrin, [11] Ito,and Bode [12] demonstrated the mild and concise synthesis of acylborons by means of chemoselective oxidative fragmentation of alkenyl N-methyliminodiacetyl (MIDA) boronates,e ither by dihydroxylation/meta-periodate cleavage or direct ozonolysis.Y et, the linear synthetic sequence involved may greatly compromise the overall efficiency as well as the diversity of the products.Herein, we report our realization of ad ivergent acylboron synthesis by an unexpected nucleophilic ring-opening/substitution reaction of MIDA a-chloroepoxyboronates (Scheme 1b). Nevertheless,p revious studies by the groups of Yudin, [15] Burke, [16] and Gevorgyan [17] indicated the 1,2-boryl migration might be acompeting side reaction (Scheme 1d). Our inspiration for this design was drawn from the rearrangement reaction of a-haloepoxysilanes,d isclosed by Utimoto and Oshima two decades ago.…”

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confidence: 99%

Diversity‐Oriented Synthesis of α‐Functionalized Acylborons and Borylated Heteroarenes by Nucleophilic Ring Opening of α‐Chloroepoxyboronates

et al. 2019

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The ring-opening reactions of N-methyliminodiacetyl (MIDA) a-chloroepoxyboronates with different nucleophiles allowt he modular synthesis of ad iverse arrayo f organoboronates.T hese include seven types of a-functionalized acylboronates and seven types of borylated heteroarenes, some of which are difficult-to-access products using alternative methods.T he common synthons, a-chloroepoxyboronates, could be viably synthesized by at wo-step procedure from the corresponding alkenyl MIDAb oronates.M ild reaction conditions,g ood functional-group tolerance,a nd generally good efficiency were observed. The utility of the products was also demonstrated.There is growing interest in the chemistry of acylborons. [1] Their synthetic value,e xemplified by their involvement in chemoselective amide formation, [1b,d,2] as well as in the synthesis of borylated heterocycles [3] and a-aminoboronic acids, [4] have rendered them appealing targets in organic synthesis.T wo classic approaches toward acylboron preparation include the reaction of ab oryl metal species [5] with ac arbonyl electrophile,a nd the reaction of an acyl anion equivalent (generated under strong basic conditions) with an electrophilic boryl reagent. [2a, 6] An elegant alternative to these approaches is the Bode acylboron synthesis,wherein an electrophilic zwitterionic boronate reagent is used to react with organometallic reagents to afford potassium acyltrifluroborates (KATs). [2f, 7] Despite the great value,t he harsh reaction conditions associated with these methods eliminate their applicability in the preparation of more functionalized or complex acylboron. Very recently,B ode invented an ew trifluoroborate iminium reagent bearing at in moiety which could undergo Stille coupling with aryl-or vinylhalides to provide KATs. [8] By taking advantage of the stability of boronates with sp 3 -hybridized B, several conceptually new routes to acylborons based on the late-stage functional-group manipulation of ab oron-containing organic precursor were also developed (Scheme 1a). In this regard, the groups of Yudin and Ito reported the oxidation reaction of a-hydroxy boronates into acylboron compounds.T he key a-hydroxy boronate intermediates were prepared by Barton radical decarboxylation of MIDA a-borylcarboxylic acid, [3a] ringopening of 2-boryl oxirane, [3b] dihydroxylation of alkenyl boronates, [3c] oxidation of unsymmetrical geminal diborylalkanes, [9] and copper(I)-catalyzed borylation of aldehydes. [10] Remarkably,r ecent advances from the groups of Perrin, [11] Ito,and Bode [12] demonstrated the mild and concise synthesis of acylborons by means of chemoselective oxidative fragmentation of alkenyl N-methyliminodiacetyl (MIDA) boronates,e ither by dihydroxylation/meta-periodate cleavage or direct ozonolysis.Y et, the linear synthetic sequence involved may greatly compromise the overall efficiency as well as the diversity of the products.Herein, we report our realization of ad ivergent acylboron synthesis by an unexpected nucleophilic ring-opening/substitutio...

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mentioning

confidence: 99%

Diversity‐Oriented Synthesis of α‐Functionalized Acylborons and Borylated Heteroarenes by Nucleophilic Ring Opening of α‐Chloroepoxyboronates

et al. 2019

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“…33 Gevorgyan and co-workers recently utilized this 1,2 boryl migration in their synthesis of borylated furans. 34 …”

Section: Stereoselective Synthesis and Iterative Coupling Of Csp3 mentioning

confidence: 99%

From Synthesis to Function via Iterative Assembly of N-Methyliminodiacetic Acid Boronate Building Blocks

2015

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Small molecules can powerfully benefit society, but the study and optimization of their function is too often impeded by the time-intensive and specialist-dependent process that is typically used to make them. In contrast, general and automated platforms have been developed for peptide, oligonucleotide, and increasingly oligosaccharide synthesis, resulting in on-demand access to these molecules, even for non-specialists. A more generalized and automated approach for making small molecules could similarly help shift the rate limiting step in small molecule science from synthesis to function. Targeting this goal, we have developed a fully automated and increasingly general platform for iterative coupling of boronate building blocks. Analogous to peptide synthesis, the process involves iterative coupling of haloboronic acids protected as the corresponding N-methyliminodiacetic acid (MIDA) boronates. This platform has enabled us and other groups to access many polyene natural products, including the polyene motifs in >75% of all polyene natural products. It further allowed us to derivatize and thereby understand the powerful but also highly toxic antifungal natural product amphotericin B, which has led to the development of less toxic derivatives currently under evaluation as drug candidates. We also discovered a stereocontrolled entry into chiral, non-racemic α-boryl aldehydes, which are versatile intermediates for the synthesis of many Csp3 boronate building blocks that are otherwise difficult to access. We have also expanded the scope of the platform to include Csp3-rich, polycyclic molecules using a linear-to-cyclized strategy, in which Csp3 boronate building blocks are iteratively assembled into linear precursors that are then cyclized into the cyclic frameworks found in many natural products and natural product-like structures. Enabled by the serendipitous discovery of a catch-and-release protocol for generally purifying MIDA boronate intermediates, the platform has been automated. The synthesis of 14 distinct classes of small molecules, including pharmaceuticals, materials, and polycyclic natural products has been achieved using this new synthesis machine. It is anticipated that the scope of small molecules accessible by this platform will continue to expand via further developments in building block synthesis, Csp3 cross-coupling methodologies, and cyclization strategies.

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“…Furthermore,n aphthalen-1-yl (6n)a nd thiophen-2-yl (6o) vinyl MIDAb oronates are also substrates amenable to oxidation/trifluoromethylation. found that the addition of the radical scavenger TEMPO or BHT inhibited both reactions, [30] suggesting that radical pathways are indeed operative.I na ddition, 18 O-labeling experiments clearly demonstrated that H 2 Oi st he oxygen source for the fluorinated product;however, the oxygen in the carbonyl group of trifluoromethylated a-boryl ketones was derived from atmospheric oxygen. (1)].…”

Section: Zuschriftenmentioning

confidence: 99%

Oxidative Difunctionalization of Alkenyl MIDA Boronates: A Versatile Platform for Halogenated and Trifluoromethylated α‐Boryl Ketones

Zeng

et al. 2016

Angewandte Chemie

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The synthesis of halogenated and trifluoromethylated a-boryl ketones via ao ne-pot oxidative difunctionalization of alkenyl MIDAb oronates is reported. These novel densely functionalizedorganoborons bearing synthetically and functionally valuable carbonyl, halogen/CF 3 and boronate moieties within the same molecule are synthetically challenging for the chemist, but have great synthetic potential, as demonstrated by their applications in as traightforwards ynthesis of borylated furans.The generality of this reaction was extensively investigated. This reaction is attractive since the starting materials,alkenyl MIDAboronates,a re easily accessible.Organoborons are among the most frequently used compounds in organic synthesis and organometallic chemistry, [1] with uses in other fields such as medicine and materials science, [2] enabling diverse and useful chemical transformations,w ith some of the most well-known and important examples being the Suzuki-Miyaura [3] and Chan-Evans-Lam [4] couplings,t he Petasis reaction [5] ,a nd the Hayashi-Miyaura conjugate addition. [6] Despite their importance,t he preparation of organoborons is not trivial in organic synthesis and this is particularly true for multi-functionalized organoborons consisting of sensitive functional groups. [1, 2] With regards to enolizable carbonyls that can generate boron enolates,t here is ar apid equilibrium between the O-and Cbound forms,with the latter being much less thermodynamically stable because of the stronger OÀBb onds over CÀB bonds. [7] Hence,t he formation of C-boron enolates (a-boryl carbonyls) provides ag reater challenge to the synthetic chemist. [8] However,t hey have potentially good synthetic value because they are kinetically amphoteric,m eaning that they contain an ucleophilic site adjacent to an electrophilic center (the nucleophilic boronate and the electrophilic carbonyl) and hence exhibit multiple modes of reactivity. [9]

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1,2-Boryl Migration Empowers Regiodivergent Synthesis of Borylated Furans

Cited by 93 publications

References 48 publications

Diversity‐Oriented Synthesis of α‐Functionalized Acylborons and Borylated Heteroarenes by Nucleophilic Ring Opening of α‐Chloroepoxyboronates

Diversity‐Oriented Synthesis of α‐Functionalized Acylborons and Borylated Heteroarenes by Nucleophilic Ring Opening of α‐Chloroepoxyboronates

From Synthesis to Function via Iterative Assembly of N-Methyliminodiacetic Acid Boronate Building Blocks

Oxidative Difunctionalization of Alkenyl MIDA Boronates: A Versatile Platform for Halogenated and Trifluoromethylated α‐Boryl Ketones

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