Enantioselective Catalytic Transannular Ketone–Ene Reactions

Rajapaksa, Naomi S.; Jacobsen, Eric N.

doi:10.1021/ol401968m

Cited by 36 publications

(9 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because we only observed 8 instead of 12b from in vivo and in vitro experiments, therefore a spontaneous Alder-ene reaction may take place and convert 12b to 8 (Fig. 1 ) 21 , 22 . The selection of one component in equilibrium with another for biosynthesis is reminiscent of the biosynthesis of phosphonate from PEP, where a homocitrate synthase, FrbC, provides the thermodynamic driving force needed to pull the unfavorable PEP mutase reaction 23 .…”

Section: Resultsmentioning

confidence: 91%

A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis

et al. 2021

View full text Add to dashboard Cite

Streptoseomycin (STM, 1) is a bacterial macrolactone that has a unique 5/14/10/6/6-pentacyclic ring with an ether bridge. We have previously identified the biosynthetic gene cluster for 1 and characterized StmD as [6 + 4]- and [4 + 2]-bispericyclase that catalyze a reaction leading to both 6/10/6- and 10/6/6-tricyclic adducts (6 and 7). The remaining steps, especially how to install and stabilize the required 10/6/6-tricyclic core for downstream modifications, remain unknown. In this work, we have identified three oxidoreductases that fix the required 10/6/6-tryciclic core. A pair of flavin-dependent oxidoreductases, StmO1 and StmO2, catalyze the direct hydroxylation at [6 + 4]-adduct (6). Subsequently, a spontaneous [3,3]-Cope rearrangement and an enol-ketone tautomerization result in the formation of 10/6/6-tricyclic intermediate 12b, which can be further converted to a stable 10/6/6-tricyclic alcohol 11 through a ketoreduction by StmK. Crystal structure of the heterodimeric complex NtfO1-NtfO2, homologues of StmO1-StmO2 with equivalent function, reveals protein-protein interactions. Our results demonstrate that the [6 + 4]-adduct instead of [4 + 2]-adduct is the bona fide biosynthetic intermediate.

show abstract

Section: Resultsmentioning

confidence: 91%

A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In particular, and after the seminal report by Jacobsen dealing with an elegant example of a transannular Diels–Alder reaction under chiral oxazaborolidine catalysis, only four additional transformations have been reported up to date. Jacobsen himself described an enantioselective transannular ketone–ene reaction using a salen—Cr(III) Lewis acid catalyst and Hierseman has reported the use of Cu(II)‐bis‐oxazoline compexes as catalysts in a transannular Claisen rearrangement . Alternatively, enamine catalysis has been used by List in a transannular aldol reaction, and some of us have also very recently reported one example of a catalytic and enantioselective transannular Morita–Baylis–Hillman reaction under chiral phosphine catalysis …”

Section: Methodsmentioning

confidence: 99%

Catalytic Stereoselective Borylative Transannular Reactions

et al. 2019

View full text Add to dashboard Cite

Medium‐sized carbocycles containing an α,β‐unsaturated ketone moiety as Michael acceptor site and a ketone moiety as internal electrophilic site are ideal substrates to conduct Cu(I)‐catalyzed conjugated borylation followed by electrophilic intramolecular trapping that results into a pioneer transannular borylative ring closing reaction. The relative configuration of three adjacent stereocenters is controlled, giving access to a single diastereoisomer for a wide range of substrates tested. Moreover, when a chiral ligand is incorporated, the reaction provides enantioenriched polycyclic products with up to 99 % ee.

show abstract

“…In 2013, Jacobsen et al [92] synthesized highly enantioselective and diastereoselective transannular ketone-ene reactions using a novel Cr(III) triflate-Schiff base complex 101 a-101 d (5 mol %). They further confirmed that it could activate aldehydes in this reaction and ketones through single pot binding.…”

Section: Enantioselective Transannular Ketone-ene Reactionmentioning

confidence: 99%

Recent Advances in the Catalytic Applications of Chiral Schiff‐Base Ligands and Metal Complexes in Asymmetric Organic Transformations

Jain

Barman

2022

ChemistrySelect

View full text Add to dashboard Cite

The Schiff base and its metal complexes are extensively studied for their adaptable metal chelating properties. Their ability to alter the design and modify it for various organic and biological applications makes them versatile compounds. The chiral Schiff base and their metal complexes possess excellent stability in very high temperatures, making them a suitable candidate for organocatalysts in reactions involving harsh conditions. Besides, these chiral complexes of Schiff base can transform their chirality in the final product formed in different chemical reactions. This stereo-induction by the chiral metal complexes of Schiff base is considerably valuable for synthesizing high optically active compounds in the field of medicinal and natural product synthesis. Thus, this review emphasizes the latest and relevant literature concerning the asymmetric catalysis of chiral Schiff base ligand-metal complexes in various synthetic organic transformation reactions. The synthesis and the catalytic mechanisms of various reactions are discussed, including their enantioselectivities, diastereoselectivities, regioselectivities, and stereoselectivities of different complexes to organic transformation.

show abstract

Enantioselective Catalytic Transannular Ketone–Ene Reactions

Cited by 36 publications

References 47 publications

A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis

A [6+4]-cycloaddition adduct is the biosynthetic intermediate in streptoseomycin biosynthesis

Catalytic Stereoselective Borylative Transannular Reactions

Recent Advances in the Catalytic Applications of Chiral Schiff‐Base Ligands and Metal Complexes in Asymmetric Organic Transformations

Contact Info

Product

Resources

About