Morita Baylis Hillman Carbonates Research Articles

Pyridine-Catalyzed Chemoselective Four-Component Cascade Reaction of Aromatic Aldehydes, Malononitrile/Cyanoacetates, MBH Carbonates, and Alcohols.

An efficient pyridine-catalyzed chemoselective four-component cascade reaction of aromatic aldehydes, malononitrile/cyanoacetates, Morita-Baylis-Hillman (MBH) carbonates, and alcohols has been established. This one-pot reaction progressed in an unusual reaction with solvent participation via a Knoevenagel condensation/oxa-Michael addition/SN2' substitution sequence. This method allowed for facile access to an array of functionalized chain alkylbenzenes and dihydroquinolinones bearing one all-carbon quaternary center in moderate to excellent yields. It is worth noting that the configuration of the all-carbon quaternary center could be modulated by changing only the electron-withdrawing groups via a tandem reduction/cyclization reaction.

Amide‐Based Morita–Baylis–Hillman Carbonates for Phosphine‐Catalyzed Asymmetric (4+2) Annulation†

Comprehensive SummaryChiral phosphine‐catalyzed asymmetric (4+2) annulation of the amide‐based Morita–Baylis–Hillman (MBH) carbonates with β,γ‐unsaturated butenolides has been developed to give enantiomer‐enriched bicyclic δ‐lactam γ‐butyrolactone compounds. The amide‐based MBH carbonates were first used as acceptor and aza‐C4 synthon in phosphine catalysis. Under mild reaction conditions, a variety of amide‐based MBH carbonates and unsaturated butenolides were well tolerated to provide chiral bicyclic δ‐lactam γ‐butyrolactone derivatives in high yields with excellent enantioselectivities as well as diastereoselectivities. A plausible reaction mechanism was also proposed based on control experiments and DFT calculations.

Recent Advances in the Reaction of MBH Carbonates: Scope and Mechanism

AbstractIn recent years, Morita‐Baylis‐Hillman (MBH) carbonates have been extensively used in domino reactions for the synthesis of novel cyclic and acyclic compounds. This review highlights the progress made in the last decade in the synthesis of a series of compounds from an uncyclized reaction or annulation of MBH carbonates, which demonstrates that the excellent reactivity and high research value of MBH carbonates as representative substrates in organic synthesis. We hope the summary and understanding of the reactivity of MBH carbonates can inspire chemists to apply these substrates in the design of more efficient domino reactions, which will be beneficial for the organic synthesis and drug chemistry.

Lewis Base Controlled (4 + 3) and (4 + 2) Annulations of MBH Carbonates with Benzofuran‐derived Azadienes: Access to Highly Substituted Benzofuro[3,2‐b]azepines and Spirotetrahydroquinolines

Catalyst‐controlled switchable (4 + 3) and (4 + 2) annulation reactions of Morita–Baylis–Hillman carbonates with benzofuran‐derived azadienes have been established. Employing PCy3 as the catalyst, the reaction could provide a variety of synthetically useful benzofuro[3,2‐b]azepines in good yields (80‐92%) with excellent chemo‐ and regioselectivities via (4 + 3) cycloaddition reactions. Whereas changing the catalyst from PCy3 to DMAP, the chemo‐ and regioselectivities were switched to construct highly substituted spirotetrahydroquinoline scaffolds with three sequential stereocenters containing all‐carbon spiro‐quaternary stereocenters in excellent efficiency and diastereoselectivities (92‐96% yields with all cases > 25:1 dr) via (4 + 2) annulations. In addition, the synthetic utility of this method was further showcased by gram‐scale reactions and synthetic transformations of the product.

Asymmetric Organocatalytic Benzylation of Morita–Baylis–Hillman Carbonates with 2,4-Dinitrotoluene Derivatives

AbstractThe organocatalytic asymmetric benzylation of Morita–Baylis–Hillman (MBH) carbonates with 2,4-dinitrotoluene derivatives as nucleophiles is described. The developed reaction provides a straightforward access to functionalized 2,4-dinitrotoluene derivatives of biological and synthetic relevance. Highly functionalized products have been chemoselectively and efficiently obtained in good to high yields (up to 84%) and with excellent stereoselectivity (up to >20:1 dr, >99 ee).

Phosphine-Catalyzed Asymmetric Allylic Alkylation of Isoxazol-5(4H)-ones with Morita-Baylis-Hillman Carbonates

Aims: Phosphine-catalyzed asymmetric allylic alkylation of isoxazol-5(4H)-ones with achiral Morita-Baylis-Hillman (MBH) carbonates has been developed. A series of isoxazol-5(4H)- ones bearing all-carbon quaternary stereocenters were obtained in 55-96% yield with 75-90% ee. Gram-scale reaction and further transformation of allylation products were conducted to demonstrate the synthetic practicability. Methods: Under Ar atmosphere, the mixture of isoxazol-5-one 1 (0.1 mmol), MBH carbonate 2 (0.12 mmol, 1.2 equiv), catalyst P5 (10 mol%), and 4Å MS (10 mg) in toluene (1 mL) was stirred at 0 oC for 24 h. The solvent was removed under vacuum, and the residue was purified by flash chromatography (petroleum ether/ethyl acetate = 3/1) to provide product 3. Result and Conclusion: We developed an efficient and enantioselective allylic alkylation of isoxazol- 5(4H)-ones with achiral MBH carbonates in the presence of chiral phosphine catalyst. A broad range of isoxazol-5(4H)-ones bearing all-carbon quaternary stereocenters were prepared with high efficiency and enantioselectivity. Importantly, the organocatalytic δ-stereocontrol of MBH carbonates was achieved via the synthetic strategy.

DABCO-catalyzed branched N-allylic substitution of lactams and related unsaturated heteroaromatics

A mild and efficient method for the synthesis of branched N-allylic lactams and related N-heteroaromatics was reported. This strategy involves a DABCO-catalyzed SN2′-SN2′ type N-allylic alkylation with Morita−Baylis−Hillman (MBH) carbonates. A wide scope of lactams and related N-heterocycles as well as MBH carbonates are well tolerated, and various branched N-substituted products were obtained in moderate to excellent yields. The utility of this method was further demonstrated by the gram-scale synthesis and diverse transformation of the products.

Cooperative Gold(I)/DMAP Catalysis Enabled (2 + 3) Cycloadditions of Yne-Enones with Oxindole-Derived MBH Carbonates.

A cooperative gold(I)/DMAP system catalyzes the (2 + 3) cycloadditions of yne-enones with oxindole-derived Morita-Baylis-Hillman (MBH) carbonates, yielding diverse bispiro-cyclopentene oxindole products. The mild, scalable protocol demonstrates broad substrate scope and excellent chemo- and diastereoselectivity. Mechanistic study reveals pivotal roles of both catalysts in the unique (2 + 3) cycloaddition. This strategy showcases superiority in achieving transformation with unique chemoselectivity and excellent diastereoselectivity, unattainable through traditional monocatalytic methodologies.

Phosphine‐Catalyzed Domino Annulation Reactions of o‐Aminotrifluoroacetophenone Derivatives with Morita–Baylis–Hillman Carbonates: Construction of Tetrahydrofuro[3,2‐b]indolines

AbstractThe domino annulation reactions of o‐aminotrifluoroacetophenone derivatives and MBH carbonates enabled by PPh3 have been reported, which provide a series of tetrahydrofuro[3,2‐b]indolines containing a CF3‐substituted tetrasubstituted carbon stereocenters in yields of 74 to 95% and >20:1 dr. In this process, MBH carbonates were used as C1/C3 synthons. The MTT assay shows that the products exhibit the activity of inhibitory effect on proliferation on Hela cancer cell line.

Chiral Phosphine Ligands of COAP and SKP Switched Regiodivergent Asymmetric Allylic Alkylation of MBH Adducts.

The palladium-catalyzed highly regioselective asymmetric allylic alkylation of 3'-indolyl-3-oxindole derivatives with Morita-Baylis-Hillman (MBH) carbonates was developed to facilely construct chiral 3,3'-bisindole derivatives under mild reaction conditions. The regioselectivity (α/γ) of MBH carbonates was efficiently switched in the presence of chiral oxalamide phosphine or spiroketal-based diphosphine/Pd(0) complexes as a chiral catalyst. A series of multifunctional 3,3'-bisindole derivatives with all-carbon quaternary stereogenic centers were obtained in high yields with good to excellent enantio-, diastereo-, and regioselectivity. The present process is endowed with some salient features such as broad substrate scope, N-protecting group-free, excellent stereoselectivity, as well as adjustable regioselectivity.

DABCO-catalyzed mono- and bisallylation of β,γ-unsaturated ketones with Morita–Baylis–Hillman carbonates

Mono- and bisallylation of β,γ-unsaturated ketones with MBH carbonates in the presence of DABCO at rt, offered α-2-alkoxycarbonyl, α,α-di(2-alkoxycarbonyl) and α,γ-di(2-alkoxycarbonyl) α,β-unsaturated ketones in the moderate to excellent yields.

Phosphine-catalyzed (3+3) annulation of cinnamaldehyde-derived Morita-Baylis-Hillman carbonates with dinucleophiles.

The phosphine-catalyzed (3+3) annulation reaction of cinnamaldehyde-derived Morita-Baylis-Hillman (MBH) carbonates with 1,3-dicarbonyl compounds as dinucleophiles has been developed, giving hexahydrochromenone derivatives in high yields with moderate to good diastereoselectivities. The reaction worked through double conjugate addition of 1,3-dicarbonyl compounds to the phosphonium intermediates generated from the cinnamaldehyde-derived MBH carbonates.

Late-stage peptide modification and macrocyclization enabled by tertiary amine catalyzed tryptophan allylation.

Late-stage modification of peptides could potentially endow peptides with significant bioactivity and physicochemical properties, and thereby provide novel opportunities for peptide pharmaceutical studies. Since tryptophan (Trp) bears a unique indole ring residue and plays various critical functional roles in peptides, the modification methods for tryptophan were preliminarily developed with considerable progress via transition-metal mediated C-H activation. Herein, we report an unprecedented tertiary amine catalyzed peptide allylation via the SN2'-SN2' pathway between the N1 position of the indole ring of Trp and Morita-Baylis-Hillman (MBH) carbonates. Using this method that proceeds under mild conditions, we demonstrated an extremely broad scope of Trp-containing peptides and MBH carbonates to prepare a series of peptide conjugates and cyclic peptides. The reaction is amenable to either solid-phase (on resin) or solution-phase conditions. In addition, the modified peptides can be further conjugated with other biomolecules at Trp, providing a new handle for bioconjugation.

Phosphine‐Catalyzed [4+3] Annulation Reaction of Indole Derivatives with MBH Carbonates: A Facile Access to Indole‐1,2‐fused 1,4‐Diazepinones and Azepines

Comprehensive SummaryA phosphine‐catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors, in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole‐1,2‐fused 1,4‐diazepinones and azepines in good to high yields in one step, which illustrates potential synthetic utilities in drug discovery.

Phosphine-Catalyzed (3 + 2) Annulation of γ-Substituted Cinnamic Aldehyde-Derived Morita-Baylis-Hillman Carbonates through Remote Activation.

A series of γ-substituted Morita-Baylis-Hillman (MBH) carbonates were synthesized and subjected to phosphine-catalyzed annulations with electrophilic exocyclic alkenes, giving various valuable spirocyclopentenes in moderate to excellent yields with moderate to excellent diastereoselectivities. A large scope of MBH carbonates bearing γ-hydrogen, alkenyl, and alkynyl substituents was well tolerated. The annulation unprecedentedly involves β-, γ-, and δ-carbons of MBH carbonates.

An Efficient Route to Access Spirooxindole–Pyrazolone-Fused Cyclopentenes by a Diastereoselective [3+2] Annulation

AbstractA DMAP-catalyzed, highly diastereoselective, [3+2] cycloaddition of pyrazolone-derived Morita–Baylis–Hillman carbonates to 3-methyleneoxindoles has been developed. A variety of structurally diverse and complex spiropyrazolone-fused oxindoles bearing three contiguous chiral centers have been synthesized in high yields (up to 98%) and with excellent diastereoselectivities (up to 99:1). Moreover, the synthetic potential of this protocol has been demonstrated by performing a Suzuki coupling reaction.

Lewis-Base-Catalyzed Enantioselective Formal [4 + 2] Annulations of Morita–Baylis–Hillman Carbonates: Access to Tetrahydroquinolines Derivatives

The Lewis-base-catalyzed enantioselective formal [4 + 2] annulation reaction of o-acylamino-aryl MBH carbonates and electron-deficient olefins was developed. Tetrahydroquinolines with three sequential stereogenic centers containing a quaternary stereocenter were obtained in high yields with good enantioselectivity.

Divergent Synthesis of Highly Substituted Tetrahydroquinolines and Cyclopentenes via Lewis Base Catalyzed Switchable [4 + 2] and [3 + 2] Annulations of MBH-Carbonates with Activated Olefins

A highly selective and divergent synthesis which enabled access to various complex compounds is highly attractive in organic synthesis and medicinal chemistry. Herein, we developed an effective method for divergent synthesis of highly substituted tetrahydroquinolines via Lewis base catalyzed switchable annulations of Morita-Baylis-Hillman carbonates with activated olefins. The reaction displayed switchable [4 + 2] or [3 + 2] annulations via catalyst or substrate control, providing a diverse range of architectures which contained highly substituted tetrahydroquinolines or cyclopentenes with three contiguous stereocenters bearing a quaternary carbon center in high yields with excellent diastereoselectivities and regioselectivities. Furthermore, synthetic utility of this strategy was further highlighted by gram-scale experiments and simple transformations of the products.

Chiral Phosphine Catalyzed Allylic Alkylation of Benzylidene Succinimides with Morita–Baylis–Hillman Carbonates

Owing to their unique chemical properties, α-alkylidene succinimides generally act as versatile synthons in organic synthesis. Compared with well-established annulations, nucleophilic alkylations of α-alkylidene succinimides are very limited. Accordingly, an organocatalytic allylic alkylation of α-benzylidene succinimides with Morita-Baylis-Hillman (MBH) carbonates was established. In the presence of a chiral phosphine catalyst, α-benzylidene succinimides reacted smoothly with MBH carbonates under mild conditions to furnish a series of optical active succinimides in high yields and enantioselectivities. Different from the reported results, the organocatalytic enantioselective construction of pyrrolidine-2,5-dione frameworks bearing contiguous chiral tertiary carbon centers was achieved via this synthetic strategy. Scaling up the reaction indicated that it is a practical strategy for the organocatalytic enantioselective alkylation of α-alkylidene succinimides. A possible reaction mechanism was also proposed.

Catalyst-Free α-Allylation of Dihydroisoquinolines with Morita-Baylis-Hillman Carbonates and Its Applications in the Construction of Benzo[a]quinolizidines.

In this work, a mild and efficient catalyst-free α-allylation of 3,4-dihydroisoquinoline imines with Morita-Baylis-Hillman (MBH) carbonates was reported. The scopes of 3,4-dihydroisoquinolines and MBH carbonates as well as gram-scale synthesis were investigated, and densely functionalized adducts were obtained in moderate to good yields. The synthetic utility of these versatile synthons was further demonstrated by the facile synthesis of diverse benzo[a]quinolizidine skeletons.