Iodine-Catalyzed Decarboxylative Amidation of β,γ-Unsaturated Carboxylic Acids with Chloramine Salts Leading to Allylic Amides

The iodine-catalyzed decarboxylative amidation of β,γ-unsaturated carboxylic acids with chloramine salts is described. This method enables the regioselective synthesis of allylic amides from various types of β,γ-unsaturated carboxylic acids containing substituents at the α- and β-positions. In the reaction, N-iodo-N-chloroamides, generated by the reaction of a chloramine salt with I2 , function as a key active species. The reaction provides an attractive alternative to existing methods for the synthesis of useful secondary allylic amine derivatives.

Highly Enantioselective Access to Primary Propargylamines: 4-Piperidinone as a Convenient Protecting Group

[reaction: see text] We report a highly enantioselective, catalytic three-component coupling of aldehydes, alkynes, and 4-piperidone hydrochloride hydrate to afford the corresponding tertiary propargylamines in useful yields. The selective cleavage of the piperidone protecting group using either ammonia/EtOH or a polymer-supported scavenger amine furnishes primary propargylamines.

Direct addition of alkynes to imines and related CN electrophiles: A convenient access to propargylamines

Propargylic amines are highly useful building blocks in organic synthesis, and the corresponding structural motif has been found in various natural products and compounds of pharmaceutical relevance. This article provides an overview of the most significant advances in the preparation of propargylic amines via the direct addition of alkynes to imines and related carbon-nitrogen electrophiles in the presence of metal catalysts or promoters.

Cobalt-Catalyzed Hydrohydrazination of Dienes and Enynes: Access to Allylic and Propargylic Hydrazides

[reaction: see text] The cobalt-catalyzed hydrohydrazination reaction of dienes and enynes is presented. Allylic and propargylic hydrazines were obtained in synthetically useful yields (allylic amines, 60-90%; propargylic amines, 47-83%) and good chemo- and regioselectivity.

Practical Enantioselective Synthesis of β-Substituted-β-amino Esters

[reaction: see text] A practical, large-scale synthesis of a beta-amino ester 1 was developed. A chiral imine derived from (S)-phenylglycinol and 3-trimethylsilylpropanal was coupled with the Reformatsky reagent 3 with high diastereoselectivity (de > 98%) to give (SS)-4a as the major isomer. The amino alcohol residue of the coupling product 4 was oxidatively cleaved with sodium periodate in the presence of methylamine. An unusual selective oxidative cleavage of the (SS)-isomer was observed and the imine 6 was obtained with ee > 99% while the (RS)-4b isomer was not cleaved. Reaction with p-toluenesulfonic acid monohydrate allowed for the hydrolysis of the imine and the isolation of the amine as its salt. The title compound 1 was then obtained by transesterification, desilylation, and hydrochloride salt formation in a one-pot process. The method was successfully applied toward the synthesis of a wide variety of beta-amino esters.

Zn-Alkynylide Additions to Acyl Iminiums

[reaction: see text] A new addition reaction of zinc-alkynylides to N-acyl and N-phosphinoyl iminiums is reported. These can be prepared in situ from imines with acid halides in the presence of a Zn-acetylide. The reaction is general with regard to imine, alkyne, and acid halides, allowing access to a large number of differentially protected propargylic amines.

Enantioselective synthesis of propargylamines through Zr-catalyzed addition of mixed alkynylzinc reagents to arylimines

[reaction: see text] Addition of mixed alkynylzinc reagents to various arylimines is catalyzed by chiral amino acid-based ligand 1 and Zr(Oi-Pr)(4).HOi-Pr to afford chiral propargylamines in up to 90% ee. Oxidative removal of the o-anisidyl group affords the free amine, which can then be acylated.

Direct addition of TMS-acetylene to aldimines catalyzed by a simple, commercially available Ir(I) complex

A new, convenient procedure for the addition reaction of trimethylsilylacetylene to imines is described. Simply treating a solution of aldimine and trimethylsilyl acetylene with catalytic [IrCl(COD)](2) furnishes the adduct in preparatively useful yields. Interestingly, the reaction may be conducted in the absence of solvent. [reaction: see text]

Asymmetric Addition of Alkyllithium to Chiral Imines: alpha-Naphthylethyl Group as a Chiral Auxiliary

The diastereoselective nucleophilic addition of alkyllithium to N-alkylidene-alpha-naphthylethylamine was carried out. In the presence of Lewis acids or Lewis bases, organolithiums reacted smoothly with imines to give the corresponding amines in high stereoselectivity (up to 100% de). Furthermore, the resulting optically active amines were found to be useful for asymmetric reactions as chiral ligands.