16206-31-8

Shuttle catalysis has emerged as a useful methodology for the reversible transfer of small functional groups, such as CO and HCN, and goes far beyond transfer hydrogenation chemistry. While a biocatalytic hydrogen-borrowing methodology is well established, the biocatalytic borrowing of alternative functional groups has not yet been realized. Herein, we present a new concept of amine borrowing via biocatalytic shuttle catalysis, which has no counterpart in chemo-shuttle catalysis and allows efficient intermolecular amine shuttling to generate reactive intermediates in situ. By coupling this dynamic exchange with an irreversible downstream step to displace the reaction equilibrium in the forward direction, high conversion to target products can be achieved. We showcase the potential of this amine-borrowing methodology using a biocatalytic equivalent of both the Knorr-pyrrole synthesis and Pictet-Spengler reaction.

Electrochemical ring-contraction of HEs and theirs pyridine derivatives is developed to obtain polysubstituted pyrroles. This process provides an orthogonal utilization of Hantzsch esters for the well-documented application as side chain or hydrogen donors. The formal transformation shows an extrusion of ethyl acetate out of the pyridine ring in a single step. In addition to the novel transformation, we also discovered the Lewis acid's intermolecular control of regioselectivity during an intramolecular electrochemical process. The reaction provides a number of polysubstituted pyrroles that have never been accessed, including pharmaceutical intermediates and photoswitches. An unusual 4-electron continuous reduction drives the unprecedented anionic dearomatization/ring-contraction/rearomatization pathway.

Herein we report the biocatalytic synthesis of substituted pyrazines and pyrroles using a transaminase (ATA) to mediate the key amination step of the ketone precursors. Treatment of α-diketones with ATA-113 in the presence of a suitable amine donor yielded the corresponding α-amino ketones which underwent oxidative dimerization to the pyrazines. Selective amination of α-diketones in the presence of β-keto esters afforded substituted pyrroles in a biocatalytic equivalent of the classical Knorr pyrrole synthesis. Finally we have shown that pyrroles can be prepared by internal amine transfer catalyzed by a transaminase in which no external amine donor is required.

The novel and efficient selenium-catalyzed reductive N-heterocyclization of γ-nitro substituted carbonyl compounds with carbon monoxide has been developed. Various multisubstituted 1H-pyrroles can be easily prepared by this protocol. The one-pot synthesis

The iron-catalyzed addition and cyclization of the Blaise reaction intermediate and nitroolefins to synthesize highly functionalized NH-pyrroles in a tandem one-pot manner from nitriles has been developed. This reaction shows good functional group tolerance and affords a broad spectrum of substituted NH-pyrroles in good yields. Copyright

(Chemical Equation Presented) Several tetrasubstituted N - H pyrroles, functionalized with ester or ketone groups at C-3 position, were prepared by one-pot coupling of secondary propargylic alcohols with 1,3-dicarbonyl compounds and tert-butyl carbamate,

A convenient one-pot propargylation/amination/cycloisomerization tandem process has been developed for the synthesis of highly substituted pyrroles derivatives from propargylic alcohols, 1,3-dicarbonyl compounds and primary amines using indium(III) chloride as a multifunctional catalyst. This method provides a flexible and rapid route to substituted pyrroles.

N-Methoxy-N-methyl-α-enaminocarboxamides were prepared starting from enamines and Weinreb α-aminoamides. Their reaction with oganometallic compounds and subsequent cyclization constitute a versatile alternative in the Knorr pyrrole synthesis.

3-Pyrrolecarboxylates 4 can be prepared from α-nitroolefins 1 and acetoacetates 2 by two methods: (a) 1 and 2 react to give 4,5-dihydro-5-methyleneamino-3-furancarboxylates 3 which are hydrolyzed, (b) the nitronic acids 8, adducts of 1 and 2, yield with different reduction agents the heterocycles 4.