Formal Synthesis of (−)-Codeine by Application of Temporary Thio Derivatization

Concise Total Synthesis of (-)-Codeine

Codeine and morphine are among the few natural products that are used directly as drugs for medical treatment. However, the availability of these is widely dependent on natural resources. Herein, we report an efficient enantioselective seven-step synthesis of (-)-codeine starting from simpler starting materials. The key steps involve microwave-assisted intramolecular cascade double heck cyclization to access the ABCE ring of opium alkaloids with the required stereocenters in one pot. A photoinduced intramolecular hydroamination of carboxamide forms the D ring and completes the pentacyclic core of the morphinans. Following that, an oxidation followed by global reduction leads to the formation of (-)-codeine. Our synthesis relies on simple and classical reactions to address the opium alkaloids and will serve as an efficient route to access the other morphinans.

Synthetic Modification and Insecticidal Activity of 4-epi-cis-Dihydroagarofuran Derivatives

To synthesize the fundamental framework of dihydroagarofuran, a novel strategy was devised for constructing the C-ring through a dearomatization reaction using 6-methoxy-1-tetralone as the initial substrate. Subsequently, the dihydroagarofuran skeleton was assembled via two consecutive Michael addition reactions. The conjugated diene and trans-dihydroagarofuran skeleton were modified. The insecticidal activities of 33 compounds against Mythimna separata were evaluated. Compounds 11-5 exhibited an LC50 value of 0.378 mg/mL. The activity exhibited a remarkable 29-fold increase compared to positive control Celangulin V, which was widely recognized as the most renowned natural dihydroagarofuran polyol ester insecticidal active compound. Docking experiments between synthetic compounds and target proteins revealed the shared binding sites with Celangulin V. Structure-activity relationship studies indicated that methyl groups at positions C4 and C10 significantly improved insecticidal activity, while ether groups with linear chains displayed enhanced activity; in particular, the allyl ether group demonstrated optimal efficacy. Furthermore, a three-dimensional quantitative structure-activity relationship model was established to investigate the correlation between the skeletal structure and activity. These research findings provide valuable insights for discovering and developing dihydroagarofuran-like compounds.

Dearomative Access to (-)-Thebaine and Derivatives

A synthesis of the natural product thebaine is reported in eight steps from commercially available starting materials, hinging on the dearomatization and coupling of simple aromatic starting materials. This provides divergent access to two unnatural opioid derivatives and is aimed at the long-term development of synthetic opioid analogs of the "wonderdrug" Naloxone. Additionally, a formal enantioselective synthesis of all reported targets is disclosed that leverages a catalytic asymmetric dearomatization via anion-pairing catalysis.

Recent Advances in Organocatalyzed Asymmetric sulfa-Michael Addition Triggered Cascade Reactions

The sulfa-Michael addition reaction is a crucial subset of the Michael addition reaction, and aroused the interest of numerous synthetic biologists and chemists. In particular, sulfa-Michael addition triggered cascade reaction has developed quickly in recent years because it offers an efficient method to construct C-S bonds and other bonds in one approach, which is widely applicable for building chiral pharmaceuticals, their intermediates, and natural compounds. This review emphasizes the recent advancements in sulfa-Michael addition-triggered cascade reactions for the stereoselective synthesis of sulfur-containing compounds, including sulfa-Michael/aldol, sulfa-Michael/Henry, sulfa-Michael/Michael, sulfa-Michael/Mannich and some sulfa-Michael triggered multi-step processes. Moreover, some reaction mechanisms and derivatization experiments are introduced appropriately.

Total Synthesis of (±)-Spiroaxillarone A via a Reversible Sulfa-Michael Addition

A bioinspired strategy is described for the total synthesis of spiroaxillarone A, which exhibited significant antimalarial activity against resistant Plasmodium falciparum (IC₅₀ = 2.32 μM). The key steps include an intermolecular ethanethiol Michael addition, o-quinone Michael addition, and subsequent β-ethanethiol elimination. This synthetic sequence provides a potential biosynthetic pathway of spiroaxillarone A.

Morphine alkaloids: History, biology, and synthesis

This chapter provides a short overview of the history of morphine since it's isolation by Sertürner in 1805. The biosynthesis of the title alkaloid as well as all total and formal syntheses of morphine and codeine published after 1996 are discussed in detail. The last section of this chapter provides a detailed overview of medicinally relevant derivatives of the title alkaloid.

Deconstructive Asymmetric Total Synthesis of Morphine-Family Alkaloid (-)-Thebainone A

Herein, we describe the development of a deconstructive strategy for the first asymmetric synthesis of (-)-thebainone A, capitalizing on an enantioselective C-C bond activation and a C-O bond cleavage reaction. The rhodium-catalyzed asymmetric "cut-and-sew" transformation between sterically hindered trisubstituted alkenes and benzocyclobutenones allowed efficient construction of the fused A/B/C rings and the quaternary center of the natural product. The newly optimized conditions show broad substrate scope and excellent enantioselectivity (up to 99.5:0.5 er). Taking advantage of boron-mediated ether bond cleavage, we completed the synthesis of the morphine alkaloid (-)-thebainone A by two complementary routes.

Diastereodivergent Synthesis of 2-Ene-1,4-hydroxy Sulfides from 2-Sulfinyl Dienes via Tandem Sulfa-Michael/Sulfoxide-Sulfenate Rearrangement

The highly diastereoselective sulfa-Michael addition of thiolates to enantiopure 2-sulfinyl dienes leads to anti or syn 2-ene-1,4-hydroxy sulfides in good yields and selectivities dependent on the reaction conditions in a diastereodivergent process. Synthetic applications of these enantiopure hydroxy sulfides by subsequent sigmatropic rearrangements have been outlined.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Total Synthesis of (±)-Thebainone A by Intramolecular Nitrone Cycloaddition

Using an intramolecular nitrone cycloaddition and a Heck cyclization as the crucial transformations, a total synthesis of the racemic morphine alkaloid thebainone A was accomplished in 22 steps commencing with isovanillin.

Synthesis and Formation Mechanism of a Compound with an Unprecedented Skeleton: Dodecahydro-4,10:5,9-diepoxydipyrrolo[3,4-b:3',4'-f][1,5]diazocine

The reaction of N-(2-{[(tert-butyldimethylsilyl)oxy]imino}ethyl)-4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide (6b) with BF3·OEt2 afforded a compound with an unprecedented dodecahydro-4,10 : 5,9-diepoxydipyrrolo[3,4-b:3',4'-f][1,5]diazocine skeleton (7) after aqueous work-up. The formation mechanism of meso-7 appears to involve dimerization of the hydrated forms (6aS)-C and (6aR)-C of the initial racemic product 9 via cation B generated by facile protonation at the C3a position of 9. Extensive computational studies revealed that the driving force of the facile hydration of 9 is probably release of the ring strain of 9, which arises in part from the bent sp2-hybridized C3a carbon.

Enantioselective synthesis of cis-hydrobenzofurans bearing all-carbon quaternary stereocenters and application to total synthesis of (‒)-morphine

(‒)-Morphine, which is selected as an essential medicine by World Health Organization, is widely applied in the treatment of the pain-related diseases. Due to its synthetically challenging molecular architecture and important clinical role, extensive synthetic studies of morphine-type alkaloids have been conducted. However, catalytic asymmetric total synthesis of (‒)-morphine remains a long-standing challenge. Here, we disclose an efficient enantioselective total synthesis of (‒)-morphine in a longest linear sequence of 16 steps. The key transformation features a highly enantioselective Robinson annulation enabled by our spiro-pyrrolidine catalyst to rapidly construct the densely functionalized cis-hydrodibenzofuran framework containing vicinal stereocenters with an all-carbon quaternary center. This asymmetric approach provides an alternative strategy for the synthesis of (‒)-morphine and its analogues.

(‒)-Morphine is an essential medicine selected by the World Health Organization, however its catalytic asymmetric syntheses have been rarely reported. Here, the authors developed an intramolecular enantioselective Michael addition leading to (‒)-morphine in a longest linear sequence of 16 steps.

A Nine-Step Formal Synthesis of (±)-Morphine

A nine-step stereoselective formal synthesis of (±)-morphine from readily available o-vanillin is presented. The carbocyclic structure of morphine was quickly assembled through an orchestration of the intermolecular Diels-Alder/Claisen/Friedel-Crafts sequential reaction. This approach involves many one-pot procedures and no protecting groups, and only a few chromatographic purifications are required.

A one-pot metal-free protocol for the synthesis of chalcogenated furans from 1,4-enediones and thiols

Transition-metal-free synthesis of chalcogenated furans through the sequential thiol-Michael/Paal–Knorr reaction of 1,4-enediones in the presence of a catalytic amount of p-toluene sulfonic acid has been developed.

New Strategy To Access Enantioenriched Cyclohexadienones: Kinetic Resolution of para-Quinols by Organocatalytic Thiol-Michael Addition Reactions

Existing stereoselective routes to 2,5-cyclohexadienones involve either desymmetrization of an achiral substrate or have attempted to perform an asymmetric dearomatization of a phenol. Herein, we report proof-of-principle experiments aimed at developing a kinetic resolution as an alternative method for accessing enantioenriched 2,5-cyclohexadienones. More specifically, chiral bifunctional thiourea catalysts were used to promote the addition of 2-thionapthalene into unsymmetric para-quinols. The selectivity of the kinetic resolution was found to be quite sensitive to substitution around the substrate.

Total Synthesis of the Norhasubanan Alkaloid Stephadiamine

(+)-Stephadiamine is an unusual alkaloid isolated from the vine Stephania japonica. It features a norhasubanan skeleton, and contains two adjacent α-tertiary amines, which renders it an attractive synthetic target. Here, we present the first total synthesis of stephadiamine, which hinges on an efficient cascade reaction to implement the aza[4.3.3]propellane core of the alkaloid. The α-aminolactone moiety in a highly hindered position was installed via Tollens reaction and Curtius rearrangement. Useful building blocks for the asymmetric synthesis of morphine and (nor)hasubanan alkaloids are introduced.