Stereoselective One-pot Synthesis Research Articles

One-Pot Stereoselective Synthesis of the Naphthofurano-Iminosugars via a [3 + 2] Cycloaddition Reaction.

This study presents the synthesis of novel naphthofurano-iminosugars (4) using 2,3-O-isopropylidene D-ribose tosylate (1a), anilines (2), and 1,4-benzoquinone (3a) as starting materials through key iminium ion/enamine intermediates via [3 + 2] cyclization reactions at room temperature. The reaction has unique regioselectivity and stereoselectivity with moderate to excellent yields. The adaptability of this method has been demonstrated using various substituted anilines, on which both electron-donating and electron-withdrawing groups were well employed in the reactions. Notably, the treatment of the fused multicyclic iminosugar 4 with TFA efficiently leads to an interesting unexpected pyridinium salt (8), possible via four sequential steps: deprotection of the 2,3-O-isopropylidene group, furan ring opening, dehydration condensation of the OH groups, and elimination of water.

Modular and Stereoselective One-Pot Total Synthesis of Icosasaccharide Motif from Cordyceps sinensis EPS-1A Glycan.

The first stereoselective one-pot synthesis of the icosasaccharide motif of EPS-1A glycan from Cordyceps sinensis has been achieved. The synthetic approach highlights the following features: (1) merging reagent modulation and remote anchimeric assistance α-glycosylation strategy for the highly stereoselective formation of five and ten continuous 1,2-cis glucosidic bonds; (2) the strategic employment of glycosyl N-phenyltrifluoroacetimidates and glycosyl o-(1-phenylvinyl)benzoates as the matched pair for efficient orthogonal one-pot synthesis; and (3) [11 + 8 + 1] orthogonal one-pot glycosylation for the efficient assembly of the target icosasaccharide.

One-Pot Stereoselective Synthesis of Furantetrahydroquinoline Derivatives Using d/l-Ribose with a 2,3-O-Isopropylidene Group.

An efficient and convenient strategy has been successfully developed for the preparation of novel furantetrahydroquinoline derivatives using d/l-ribose with a 2,3-O-isopropylidene group through the aza-Diels-Alder mechanism. This method has high atom and step economy, high stereoselectivity, and gram-scale synthesis (yield 67%).

Regio and Stereoselective One-Pot Synthesis of 2-Deoxy-3-thio Pyranoses and Their O-Glycosides from Glycals.

A reaction of glycals with two different types of nucleophiles in the presence of SnCl4 enabled one-pot rapid access to 2-deoxy-3-thio pyranoses and their O-glycosides. The process involves thioaryl substitution at C-3 with stereoretention and α-selective O-glycosylation at C-1 from d-glycals, thus combining two reactions with three interventions. The present methodology features an attractive three-component coupling (1:1.2:1.5 ratio) with operational simplicity at 0 °C in 10-20 min. This stereoselective one-pot 1,3-difunctionalization approach of glycals is compatible with wide range of primary and secondary alcohols affording products in good to excellent yields. This methodology was successfully extended toward disaccharide synthesis. Several control experiments suggested a plausible reaction mechanism and rationale behind regio and stereoselectivity. The reaction strategy possesses an intrinsic ability for the synthesis of various natural products and drug molecules.

One‐Pot Construction of Sulfonyl Benzonorcaradienes

One-pot stereoselective synthesis of strained sulfonyl benzonorcaradienes proceeds through base-mediated tandem annulation of o-bis-sulfonylmethyl arenes with diversified chalcones (α,β-unsaturated carbonyls) via intermolecular desulfonylative cyclopropanation, followed by intramolecular condensation. A plausible mechanism is proposed and discussed. The proposed synthetic route forms two carbon–carbon single (C–C) bonds and one carbon–carbon double (C=C) bond.

Regio- and Stereoselective One-Pot Synthesis of New Heterocyclic Compounds with Two Selenium Atoms Based on 2-Bromomethyl-1,3-thiaselenole Using Phase Transfer Catalysis

To date, not a single representative of 2,3-dihydro-1,4-thiaselenin-2-yl selenides has been described in the literature. The reaction of 2-bromomethyl-1,3-thiaselenole with potassium selenocyanate at low temperature was accompanied by a rearrangement with ring expansion leading to six-membered 2,3-dihydro-1,4-thiaselenin-2-yl selenocyanate, which was used for the generation of sodium dihydro-1,4-thiaselenin-2-yl selenolate. The latter intermediate was involved in situ in the nucleophilic substitution and addition reactions under phase transfer catalysis conditions. The nucleophilic substitution reactions with alkyl halides gave alkyl, allyl and propargyl 2,3-dihydro-1,4-thiaselenin-2-yl selenides in 93–98% yields. The addition reactions of dihydro-1,4-thiaselenin-2-yl selenolate anion to alkyl acrylates, acrylonitrile and alkyl propiolates proceeded in a regio- and stereoselective fashion affording corresponding functionalized 2,3-dihydro-1,4-thiaselenin-2-yl selenides in 93–98% yields. Thus, the regio- and stereoselective one-pot synthesis of a novel family of 2,3-dihydro-1,4-thiaselenin-2-yl selenides has been developed based 2-bromomethyl-1,3-thiaselenole, potassium selenocyanate, alkyl halides and compound with activated double and triple bonds.

Stereoselective one-pot five-component synthesis of polysubstituted 1,4,5,6-tetrahydropyridines with two and three stereocenters

Stereoselective one-pot five-component synthesis of polysubstituted 1,4,5,6-tetrahydropyridines with two and three stereocenters

One-Pot Stereoselective Synthesis of 2,3-Diglycosylindoles and Tryptophan-C-glycosides via Palladium-Catalyzed C-H Glycosylation of Indole and Tryptophan.

We described a novel palladium-catalyzed C-H glycosylation of indole or tryptophan for a one-pot stereoselective synthesis of 2,3-diglycosylindoles and tryptophan-C-glycosides. In this strategy, the use of air and base-free and ligand-free conditions provided a highly efficient route to construct C-glycosides. The method can be applied to a wide range of cost-effective and convenient glycosyl chloride donors. Mechanistic studies indicated that the indole 2,3-diglycosylation sequence was C3 and then C2.

Stereoselective synthesis and investigation of mechanism of trifluoromethylated cyclopropylphosphonate

Herein, we would like to present a one-pot stereoselective synthesis of a trisubstituted trifluoromethylated cyclopropylphosphonate derivative. The title compound was obtained using a Michael initiated ring closure protocol. NMR studies, as well as DFT calculations, confirmed preference of the reaction for the formation of only one isomer. This new building block can be used as a potential tool for development of a novel class of drugs.

An Efficient One-pot Stereoselective Synthesis of 2,6-disubstituted 4-thiocyanatotetrahydropyrans

An efficient stereoselective synthesis of 2,6-disubstituted-4-thiocyanatotetrahydropyrans has been developed through a one-pot three-component reaction of aldehydes, trimethyl allylsilane, and NH<sub>4</sub>SCN in the presence of BF<sub>3</sub>.Et<sub>2</sub>O at room temperature. The products are formed rapidly (10-30 min) in excellent yields (78-98%).

Water-controlled selectivity switch in a multicomponent reaction: One-pot stereoselective synthesis of (acyloxymethylidene)chromonyl-furochromones and amido-(acyloxymethylidene)chromones

An efficient protocol for the selective synthesis of (acyloxymethylidene)chromonyl-furochromones or amido-(acyloxymethylidene)chromones via a water-controlled multicomponent cascade reaction of 3-formylchromones, linear carboxylic acid anhydrides, and alkyl isocanides in CH2Cl2 has been developed. (Acyloxymethylidene)chromonyl-furochromones were obtained in dry CH2Cl2; conversely, amido-(acyloxymethylidene)chromones were formed with wet CH2Cl2 (undried dichloromethane) as the solvent at room temperature. The reaction proceeds via the formation of a highly reactive O-acylatedoxonium intermediate, generated from the reaction between 3-formylchromones and linear carboxylic acid anhydrides. The subsequent trapping of the O-acylatedoxonium ion by aminofurochromone intermediate in situ generated by cycloaddition reaction of alkyl isocyanide and the second equivalent of 3-formylchromone in dry CH2Cl2, would give (acyloxymethylidene)chromonyl-furochromones in excellent diastereoselectivity and yields. Alternatively, O-acylatedoxonium intermediate could be also regioselectively trapped by α-addition of alkyl isocyanides in wet CH2Cl2 to provide amido-(acyloxymethylidene)chromones in good yields.

Stereoselective one-pot synthesis of multi-substituted (2Z,4E)-2,4-dienamides from ketene dithioacetal and their solid-state fluorescence

Stereoselective one-pot synthesis of multi-substituted (2Z,4E)-2,4-dienamides from ketene dithioacetal and their solid-state fluorescence

Reactions of CF3-Haloenones with 1,3-Dicarbonyl Compounds: Chemo- and Stereoselective Assembly of Fluorinated Dihydrofurans

The chemo- and stereoselective one-pot synthesis of functionalized trifluoromethylated 4,5-dihydrofurans was developed. It consists in the treatment of fluorinated 2-haloenones with 1,3-dicarbonyl compounds (1,3-diketones and β-keto esters). The reaction was generally found to proceed in moderate to good yield and excellent selectivity. The mechanism of the assembly of these heterocycles is discussed in terms of multi-step processes involving formation of Michael adduct followed by cyclization through the classical intramolecular halogen nucleophilic substitution at sp3 carbon atom.

Multicatalytic Approach to One-Pot Stereoselective Synthesis of Secondary Benzylic Alcohols.

One-pot procedures bear the potential to rapidly build up molecular complexity without isolation and purification of consecutive intermediates. Here, we report multicatalytic protocols that convert alkenes, unsaturated aliphatic alcohols, and aryl boronic acids into secondary benzylic alcohols with high stereoselectivities (typically >95:5 er) under sequential catalysis that integrates alkene cross-metathesis, isomerization, and nucleophilic addition. Prochiral allylic alcohols can be converted to any stereoisomer of the product with high stereoselectivity (>98:2 er, >20:1 dr).

Copper-Catalyzed One-Pot Synthesis of 1,3-Enynes from 2-Chloro-N-(quinolin-8-yl)acetamides and Terminal Alkynes.

A method for the chemo-, regio-, and stereoselective one-pot synthesis of 1,3-enynes is described. The reaction of 2-chloro-N-(quinolin-8-yl)acetamides with terminal alkynes proceeds smoothly in the presence of a copper catalyst at room temperature to produce (E)-1,3-enynes in satisfactory to excellent yields. The mechanism study reveals that the cross-dimerization of internal alkynes generated in situ with terminal alkynes proceeds via allene intermediates. The directing group 8-aminoquinoline plays a key role in the current selective synthesis of (E)-1,3-enynes.

Stereoselective synthesis of para-quinone monoketals through tri-bromide (TBr) mediated oxidative dearomatization of phenols

A metal free one-pot stereoselective synthesis of para-quinone monoketals and their derivatives has been reported in this present work. Tri-bromides (TBrs) have been employed as an effective reagent for intramolecular spirocyclizations leading to excellent yields of the monoketals. The TBrs are slowly turning out to be an important reagent for oxidative dearomatization which is further attested in the presented work. In addition, the obtained substituted para-quinone monoketals and their derivatives were readily transformed into more complex products by reaction with Pd/C under hydrogen atmosphere leading to saturated para-monoacetal, which are important building blocks in organic synthesis.

Artificial Intelligence-Designed Stereoselective One-Pot Synthesis of trans-β-Lactams and Its Application to Cholesterol Absorption Inhibitor SCH 47949 Synthesis

Artificial Intelligence-Designed Stereoselective One-Pot Synthesis of trans-β-Lactams and Its Application to Cholesterol Absorption Inhibitor SCH 47949 Synthesis

Diastereoselective multi-component tandem condensation: synthesis of 2-amino-4-(2-furanone)-4H-chromene-3-carbonitriles.

A general strategy for a one-pot stereoselective synthesis of 2-amino-4-(2-furanone)-4H-chromene-3-carbonitriles by reaction of salicylaldehyde, malononitrile and butenolides via a tandem Knoevenagel/Pinner/vinylogous Michael condensation is presented. The β,γ-butenolides gave a syn-selective MCR adduct with a dr up to 11.5 : 1. The mechanistic insight into the MCR was obtained by DFT calculations.

Stereoselective one-pot synthesis of polycyanosubstituted piperidines

An effective and facile multicomponent method for the synthesis of polysubstituted piperidines is described. The Michael–Mannich type cascade of benzylidenemalononitriles with aromatic aldehydes and ammonium acetate or aqueous ammonia provides convenient access to the stereoselective synthesis of 3,3,5,5-tetracyano-2,4,6-triarylpiperidines in good to excellent yields in one-pot manner. Ammonium acetate or aqueous ammonia plays a role both as a catalyst and as a nitrogen source. It is established that the reaction proceeds via sequence of equilibriums and a competitive mechanisms are implemented.

Phellilane L, Sesquiterpene Metabolite of Phellinus linteus: Isolation, Structure Elucidation, and Asymmetric Total Synthesis.

A new cyclopropane-containing sesquiterpenoid, phellilane L (1), was isolated from the medicinal mushroom Phellinus linteus ("Meshimakobu" in Japanese), a member of the Hymenochaetaceae family and a well-known fungus that is widely used in East Asia. The planar structure of 1 was determined on the basis of spectroscopic analysis. The authors achieved the first total synthesis of 1. Our protecting group-free synthesis features a highly stereoselective one-pot synthesis involving an intermolecular alkylation/cyclization/lactonization strategy for construction of the key cyclopropane-γ-lactone intermediate. Additionally, our synthesis determined the absolute configuration of phellilane L (1).