Cycloaddition Of Nonstabilized Azomethine Ylides Research Articles

3 + 2] cycloaddition of nonstabilized azomethine ylides and 2-benzothiazolamines to access imidazolidine derivatives

A simple and practical method for the construction of 1,3,5-trisubstituted imidazolidine derivatives via [3 + 2] cycloaddition reaction has been developed. This reaction could smoothly proceed between nonstabilized azomethine ylides generated in situ and 2-benzothiazolamines to deliver a wide scope of differently substituted imidazolidines in high yields (up to 98%). The structure of one example was confirmed by X-ray single-crystal structure analysis.

Three-Component [3+2] Cycloaddition for Regio- and Diastereoselective Synthesis of Spirooxindole-Pyrrolidines.

1,3-Dipolar cycloaddition of nonstabilized azomethine ylides derived from α-C-H functionalization of tetrahydroisoquinoline for regio- and diastereoselective synthesis of spirooxindole-pyrrolidines is developed. A three-component reaction of readily available cyclic amine, aryl aldehydes, and olefinic oxindoles provides a pot, atom and step economy (PASE) approach for making spiro-heterocyclic compounds with biological interest.

Sequential decarboxylative [3+2] cycloaddition and Staudinger/aza-Wittig reactions for diastereoselective synthesis of tetrahydro-pyrroloquinazolines and tetrahedro-pyrrolobenzodiazepines

A method for diastereoselective synthesis of tetrahydro-pyrroloquinazolines and tetrahydro-pyrrolobenzodiazepines is developed through sequential reactions including decarboxylative 1,3-dipolar cycloaddition of non-stabilized azomethine ylides, N-acylation or N-alkylation, and the Staudinger/aza-Wittig reactions.

Highly Efficient and Diastereoselective Construction of Tricyclic Pyrrolidine‐Fused Benzo[b]thiophene 1,1‐dioxide Derivatives via 1,3‐Dipolar [3 + 2] Cycloaddition

A rapid and highly efficient 1,3‐dipolar [3 + 2] cycloaddition of nonstabilized azomethine ylides generated in situ with benzo[b]thiophene 1,1‐dioxides as the dipolarophiles has been developed. The efficient method affords tricyclic pyrrolidine‐fused benzo[b]thiophene 1,1‐dioxide derivatives in high to excellent yields (up to 99%) with excellent diastereoselectivities (up to >25:1 dr) under mild reaction conditions. The structure of a typical product was confirmed by X‐ray crystallography.

One-Pot Synthesis of Triazolobenzodiazepines Through Decarboxylative [3 + 2] Cycloaddition of Nonstabilized Azomethine Ylides and Cu-Free Click Reactions.

A one-pot synthesis of triazolobenzodiazepine-containing polycyclic compounds is introduced. The reaction process involves a decarboxylative three-component [3 + 2] cycloaddition of nonstabilized azomethine ylides, N-propargylation, and intramolecular click reactions.

Efficient Strategy for the Construction of Both Enantiomers of the Octahydropyrroloquinolinone Ring System: Total Synthesis of (+)-Aspidospermidine.

An efficient and highly stereoselective intramolecular [3 + 2] cycloaddition of nonstabilized azomethine ylide generated from a designed bicyclic aminal precursor is reported for the synthesis of both (-)- and (+)-octahydropyrroloquinolinone. One of the enantiomers is further advanced to accomplish the total synthesis of (+)-aspidospermidine.

Asymmetric Synthesis of 1,2-Diamines bearing Tetrasubstituted Centers from Nonstabilized Azomethine Ylides and N-Sulfinylketimines under Brønsted Acid Catalysis.

The first asymmetric cycloaddition of nonstabilized azomethine ylide and N-sulfinylimines is presented. In reactions with aryl-alkyl and heteroaryl-alkyl ketimines, excellent diastereoselectivities and good yields are obtained in all cases, regardless of the electronic character of the substituents at the aromatic rings. Moreover, the cycloadducts obtained can easily be deprotected in acid media, giving access to free 1,2-diamines which are prevalent in many natural and pharmaceutical products.

Intramolecular 1,3-Dipolar Cycloaddition of Azomethine Ylides Leading to Pyrido[2,3-b]quinolines

A convenient six-step route to the previously unknown 1H-pyrrolo[2,3-f]benzo[b][1,8]naphthyridine ring system using an intramolecular 1,3-dipolar cycloaddition of nonstabilized azomethine ylides has been described.

Stereoselective One-Step Construction of Vicinal Quaternary and Tertiary Stereocenters of the 5,10b-Ethanophenanthridine Skeleton: Total Synthesis of (±)-Maritidine

The challenging vicinal quaternary and tertiary stereocenters of the 5,10b-ethanophenanthridine skeleton are created in a single step utilizing intramolecular [3 + 2]-cycloaddition of nonstabilized azomethine ylide as the key step. The application of the chemistry is demonstrated by synthesizing (+/-)-maritidine.

Stereospecific Route to 5,11-Methanomorphanthridine Alkaloids via Intramolecular 1,3-Dipolar Cycloaddition of Nonstabilized Azomethine Ylide: Formal Total Synthesis of (±)-Pancracine

The core structure of the complex pentacyclic 5,11-methanomorphanthridine alkaloids is constructed stereospecifically in one step employing an intramolecular [3 + 2]-cycloaddition of nonstabilized azomethine ylide as the key step. The strategy is demonstrated by accomplishing the formal total synthesis of (+/-)-pancracine. [reaction: see text]

A three-component, one-pot synthesis of indolizidines and related heterocycles via the [3+2] cycloaddition of nonstabilized azomethine ylides.

Nonstabilized azomethine ylides (i.e. those bearing only hydrogens or alkyl groups) can be generated from (2-azaallyl)stannanes and (2-azaallyl)silanes through an intramolecular N-alkylation/demetalation cascade. The resulting ylides undergo [3+2] cycloaddition with electron-poor or electron-rich dipolarophiles yielding indolizidines and related 1-aza[m.3.0]bicycloalkane systems in good yield. An in situ protocol allows for a one-pot, three-component synthesis of indolizidines. The (2-azaallyl)stannanes tolerate enolizable hydrogens in these cycloadditions, while (2-azaallyl)silanes do not. The mechanism of the cycloaddition cascade is clarified by a series of control experiments. The same (2-azaallyl)stannanes may be transmetalated by n-butyllithium to generate 2-azaallyllithiums, which also may undergo a [3+2] cycloaddition/N-alkylation cascade to form indolizidines.

3+2]-Cycloaddition of nonstabilized azomethine ylides, part 9: A general approach for the construction of X-azabicyclo[m.2.1]alkanes in optically pure form by asymmetric 1,3-dipolar cycloaddition reactions

A general strategy for the construction of X-azabicyclo[m.2.1]alkane frameworks in optically pure form is reported by the asymmetric [3+2]-cycloaddition reaction of cyclic azomethine ylides with Oppolzer's acryloyl camphor sultam.

First Example of Intramolecular 1,3-Dipolar Cycloaddition of Non-stabilized Azomethine Ylide Generated from Tertiary Amine N-Oxide

The reaction of two optically active 1-alkyl-3,4-diallyloxypyrrolidine 1 oxides, (9) and (15), under basic conditions has been examined. The 1-benzyl derivative (9), on reaction with lithium diisopropylamide, furnished a single pyrrolidine derivative (11) by intramolecular 1,3-dipolar cycloaddition of an N-benzylidene azomethine ylide (10), while the 1 -methyl derivative (15) reacted with tert-butyllithium in the presence of trimethylaluminum to afford only a single 7-azabicyclo[2.2.1]heptane derivative (19) by spontaneous intramolecular 1,3-dipolar cycloaddition of the endocyclic azomethine ylide (17)