scholarly journals Dimeric cyclobutane formation under continuous flow conditions using organophotoredox catalysed [2+2]-cycloaddition

2021 ◽  
Author(s):  
Helena Grantham ◽  
Marc Kimber
Keyword(s):  
Natural Products ◽  
Continuous Flow ◽  
Reaction Times ◽  
Functional Materials ◽  
Synthetic Route ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
New Class ◽  
Cyclobutane Dimers ◽  
Flow Study

Radical cation-initiated dimerization of electron rich alkenes is an expedient method for the synthesis of cyclobutanes. By merging organophotoredox catalysis and continuous flow technology a batch versus continuous flow study has been performed providing a convenient synthetic route to an important carbazole cyclobutane material dimer t-DCzCB using less only 0.1 mol% of an organophotoredox catalyst. The scope of this methodology was explored giving a new class of functional materials, as well as an improved synthetic route to styrene based lignan dimeric natural products. The cyclobutane dimers could be isolated in higher chemical yields under continuous flow conditions and reaction times were reduced significantly compared to traditional batch reaction conditions.

scholarly journals The Eschenmoser coupling reaction under continuous-flow conditions

2011 ◽  
Vol 7 ◽  
pp. 1164-1172 ◽  
Author(s):  
Sukhdeep Singh ◽  
J Michael Köhler ◽  
Andreas Schober ◽  
G Alexander Groß
Keyword(s):  
Continuous Flow ◽  
Elevated Temperatures ◽  
Reaction Times ◽  
Coupling Reaction ◽  
Flow Chemistry ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Reaction Proceeds

The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given.

scholarly journals Breaking Molecular Symmetry through Biocatalytic Reactions to Gain Access to Valuable Chiral Synthons

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1454
Author(s):  
Angela Patti ◽  
Claudia Sanfilippo
Keyword(s):  
Bioactive Compounds ◽  
Continuous Flow ◽  
Molecular Diversity ◽  
Molecular Symmetry ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Whole Cells ◽  
Efficient Approach ◽  
Substrate Tolerance ◽  
Gain Access

In this review the recent reports of biocatalytic reactions applied to the desymmetrization of meso-compounds or symmetric prochiral molecules are summarized. The survey of literature from 2015 up to date reveals that lipases are still the most used enzymes for this goal, due to their large substrate tolerance, stability in different reaction conditions and commercial availability. However, a growing interest is focused on the use of other purified enzymes or microbial whole cells to expand the portfolio of exploitable reactions and the molecular diversity of substrates to be transformed. Biocatalyzed desymmetrization is nowadays recognized as a reliable and efficient approach for the preparation of pharmaceuticals or natural bioactive compounds and many processes have been scaled up for multigram preparative purposes, also in continuous-flow conditions.

Photodecarboxylative Benzylations of N-Methoxyphthalimide under Batch and Continuous-Flow Conditions

2015 ◽  
Vol 68 (11) ◽  
pp. 1662 ◽  
Author(s):  
Hossein Mohammadkhani Pordanjani ◽  
Christian Faderl ◽  
Jun Wang ◽  
Cherie A. Motti ◽  
Peter C. Junk ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Methoxy Group ◽  
Irradiation Time ◽  
Batch Process ◽  
Flow Conditions ◽  
Reaction Conditions

A series of photodecarboxylative benzylations of N-methoxyphthalimide were successfully realised using easily accessible starting materials. The reactions proceeded smoothly and the corresponding benzylated hydroxyphthalimidines were obtained in moderate to good yields of 52–73 %. No competing photoinduced dealkoxylation of the N-methoxy group was observed. The reaction with potassium phenylacetate was subsequently investigated in an advanced continuous-flow photoreactor. The reactor allowed rapid optimization of the reaction conditions and gave the desired benzylated product in higher yield and shorter irradiation time compared with the batch process.

Exploiting photooxygenations mediated by porphyrinoid photocatalysts under continuous flow conditions

RSC Advances ◽  
2016 ◽  
Vol 6 (16) ◽  
pp. 12717-12725 ◽  
Author(s):  
Kleber T. de Oliveira ◽  
L. Zane Miller ◽  
D. Tyler McQuade
Keyword(s):  
Continuous Flow ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Long Term Experiments

Photooxygenations of naphthols under continuous flow conditions using porphyrinoids as photocatalysts are described. Reaction conditions, long-term experiments and scope were performed, thus allowing the production of substituted naphthoquinones.

Nitrile Oxide 1,3-Dipolar Cycloaddition by Dehydration of Nitromethane Derivatives Under Continuous Flow Conditions

2011 ◽  
Vol 64 (10) ◽  
pp. 1397 ◽  
Author(s):  
Malte Brasholz ◽  
Simon Saubern ◽  
G. Paul Savage
Keyword(s):  
Continuous Flow ◽  
Reaction Times ◽  
Nitro Compounds ◽  
Dipolar Cycloaddition ◽  
Flow Conditions ◽  
Nitrile Oxides ◽  
Aliphatic Nitrile ◽  
By Products ◽  
Flow Techniques

Aliphatic nitrile oxides were generated in situ, by dehydration of terminal nitro compounds, and reacted with dipolarophiles using continuous flow techniques to afford substituted isoxazolines. The yields of cycloadducts were comparable with traditional flask-based reactions but reaction times were much shorter. In-line scavenger cartridges conveniently removed by-products and unreacted reagents to give almost pure crude products. The process was demonstrated up to gram scale.

scholarly journals Metal-porphyrin catalyzed aziridination of α-methylstyrene: Batch vs. flow process

2017 ◽  
Vol 21 (04-06) ◽  
pp. 381-390 ◽  
Author(s):  
Daniela Intrieri ◽  
Sergio Rossi ◽  
Alessandra Puglisi ◽  
Emma Gallo
Keyword(s):  
Dft Calculations ◽  
Continuous Flow ◽  
Flow System ◽  
Reaction Times ◽  
Batch Process ◽  
Porphyrin Ring ◽  
Flow Conditions ◽  
Metal Porphyrin ◽  
Flow Process ◽  
Influence Of Substituents

This work describes the aziridination process of [Formula: see text]-methylstyrene by using electron poor aromatic azides in the presence of metal-based porphyrins as catalysts. Different ruthenium and cobalt-based porphyrins were successfully employed for the synthesis of [Formula: see text]-aryl aziridines performed under a traditional batch methodology and under continuous flow conditions. In general, yields obtained using ruthenium-based catalysts in a traditional batch process were higher than those observed when the reaction was performed under flow conditions. However, cobalt-based porphyrins showed better activities and short reaction times when employed in a flow system process. DFT calculations were also performed in order to understand the influence of substituents on the porphyrin ring in the aziridination process.

scholarly journals A Continuous-Flow, Two-Step, Metal-Free Process for the Synthesis of Differently Substituted Chiral 1,2-Diamino Derivatives

Synthesis ◽  
2018 ◽  
Vol 50 (07) ◽  
pp. 1430-1438
Author(s):  
Maurizio Benaglia ◽  
Margherita Pirola ◽  
Maria Compostella ◽  
Laura Raimondi ◽  
Alessandra Puglisi
Keyword(s):  
Continuous Flow ◽  
Catalytic Synthesis ◽  
Flow Conditions ◽  
Reaction Conditions ◽  
Flow Process ◽  
Preliminary Screening ◽  
Metal Free ◽  
Free Process ◽  
Continuous Flow Process ◽  
Nitro Reduction

The enantioselective organocatalytic reduction of aryl-substituted nitroenamines was successfully performed under continuous-flow conditions. After a preliminary screening with a 10-μL microreactor, to establish the best reaction conditions, the reduction was scaled up in a 0.5-mL mesoreactor, without appreciable loss of enantioselectivity, that remained constantly higher than 90%. The in-flow nitro reduction was also accomplished, either by Raney nickel catalyzed hydrogenation or by a metal-free methodology based on the use of the very inexpensive and readily available reducing agent trichlorosilane. The final aim is to develop a two-step, continuous-flow process for the stereo­selective, metal-free, catalytic synthesis of differently functionalized chiral 1,2-diamines.

scholarly journals Continuous-flow synthesis of primary amines: Metal-free reduction of aliphatic and aromatic nitro derivatives with trichlorosilane

2016 ◽  
Vol 12 ◽  
pp. 2614-2619 ◽  
Author(s):  
Riccardo Porta ◽  
Alessandra Puglisi ◽  
Giacomo Colombo ◽  
Sergio Rossi ◽  
Maurizio Benaglia
Keyword(s):  
Continuous Flow ◽  
Reaction Times ◽  
Nitro Compounds ◽  
Primary Amines ◽  
Flow Conditions ◽  
Metal Free ◽  
Nitro Derivatives ◽  
Aromatic Nitro ◽  
High Yields ◽  
First Time

The metal-free reduction of nitro compounds to amines mediated by trichlorosilane was successfully performed for the first time under continuous-flow conditions. Aromatic as well as aliphatic nitro derivatives were converted to the corresponding primary amines in high yields and very short reaction times with no need for purification. The methodology was also extended to the synthesis of two synthetically relevant intermediates (precursors of baclofen and boscalid).

Synthesis of Imines and Amines from Furfurals Using Continuous Flow Processing

2017 ◽  
Vol 70 (10) ◽  
pp. 1069 ◽  
Author(s):  
Boris Bizet ◽  
Christian H. Hornung ◽  
Thomas M. Kohl ◽  
John Tsanaktsidis
Keyword(s):  
High Temperatures ◽  
Continuous Flow ◽  
Simple Procedure ◽  
Condensation Reaction ◽  
Reaction Times ◽  
Primary Amines ◽  
Reactive Site ◽  
Flow Conditions

A simple procedure for the condensation of the bio-derived furfurals, 5-(methyl)furfural (MF) and 5-(chloromethyl)furfural (CMF), with primary amines is described herein. The experiments were conducted in both batch and flow conditions, with reaction times as short as 60 s. Moderately high temperatures were demonstrated to be suitable for the condensation reaction of MF in a few minutes whereas milder conditions and longer reaction times were necessary for CMF. Under these conditions the amine did not react with the methyl-chlorine group, leaving a very reactive site after condensation.

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