Sustainable Synthesis of Thioimidazoles via Carbohydrate-Based Multicomponent Reactions

The synthesis of diversely functionalized thioimidazoles through a modern variant of the Marckwald reaction is presented. This new protocol utilizes unprotected carbohydrates as well as simple amine salts as sustainable and biorenewable starting materials. Importantly it was discovered that a bifurcated reaction pathway results from using aldoses and ketoses respectively, yielding distinct reaction products in a highly selective manner

Continuous-Flow Hofmann Rearrangement Using Trichloroisocyanuric Acid for the Preparation of 2‑Benzoxazolinone

A continuous-flow preparation of 2-benzoxazolinone via the Hofmann rearrangement of salicylamide has been implemented employing trichloroisocyanuric acid as the stable and atom-economic chlorinating agent. The system was optimized to avoid solid accumulation and allow the preparation of hundreds of grams of the pure desired material over a working day. Furthermore, a trichloroisocyanuric acid (TCCA)-based chlorination of 2-benzoxazolone to the corresponding 5-chloro derivative was also carried out under batch conditions

Sustainable Synthesis of Thioimidazoles via Carbohydrate-Based Multicomponent Reactions

The synthesis of diversely functionalized thioimidazoles through a modern variant of the Marckwald reaction is presented. This new protocol utilizes unprotected carbohydrates as well as simple amine salts as sustainable and biorenewable starting materials. Importantly it was discovered that a bifurcated reaction pathway results from using aldoses and ketoses respectively, yielding distinct reaction products in a highly selective manner

Batch and Flow Synthesis of Pyrrolo[1,2‑<i>a</i>]‑quinolines via an Allene-Based Reaction Cascade

An efficient reaction cascade delivering a series of pyrrolo­[1,2-<i>a</i>]­quinolines bearing phosphonate or phosphine oxide moieties is presented. This sequence exploits the <i>in situ</i> transformation of propargylic alcohols into transient allenes by means of a strategic [2,3]-sigmatropic rearrangement followed by trapping of the resulting allenes by an adjacent pyrrole ring. Furthermore, the initial small scale batch process was successfully translated into a continuous flow process allowing efficient preparation of selected pyrrolo­[1,2-<i>a</i>]­quinolines on multigram scale without any safety concerns due to the reaction’s inherent exothermic profile

Flow Ozonolysis Using a Semipermeable Teflon AF-2400 Membrane To Effect Gas−Liquid Contact

A flow-through chemistry apparatus has been developed which allows gases and liquids to contact via a semipermeable Teflon AF-2400 membrane. In this preliminary investigation, the concept was proven by application to the ozonolysis of a series of alkenes

Flow Ozonolysis Using a Semipermeable Teflon AF-2400 Membrane To Effect Gas−Liquid Contact

A flow-through chemistry apparatus has been developed which allows gases and liquids to contact via a semipermeable Teflon AF-2400 membrane. In this preliminary investigation, the concept was proven by application to the ozonolysis of a series of alkenes

Flow Ozonolysis Using a Semipermeable Teflon AF-2400 Membrane To Effect Gas−Liquid Contact

A flow-through chemistry apparatus has been developed which allows gases and liquids to contact via a semipermeable Teflon AF-2400 membrane. In this preliminary investigation, the concept was proven by application to the ozonolysis of a series of alkenes

KMnO₄-Mediated Oxidation as a Continuous Flow Process

An efficient and easily scalable transformation of alcohols and aldehydes to carboxylic acids and nitroalkane derivatives to the corresponding carbonyls and carboxylic acids using permanganate as the oxidant within a continuous flow reactor is reported. Notably, the generation and downstream processing of MnO2 slurries was not found to cause any blocking of the reactor when ultrasound pulses were applied to the flow system

Safe and Reliable Synthesis of Diazoketones and Quinoxalines in a Continuous Flow Reactor

A flow method for the synthesis of aliphatic and aromatic diazoketones from acyl chloride precursors has been developed and used to prepare quinoxalines in a multistep sequence without isolation of the potentially explosive diazoketone. The protocol showcases an efficient in-line purification using supported scavengers with time-saving and safety benefits and in particular a reduction in the operator’s exposure to carcinogenic phenylenediamines

Safe and Reliable Synthesis of Diazoketones and Quinoxalines in a Continuous Flow Reactor

A flow method for the synthesis of aliphatic and aromatic diazoketones from acyl chloride precursors has been developed and used to prepare quinoxalines in a multistep sequence without isolation of the potentially explosive diazoketone. The protocol showcases an efficient in-line purification using supported scavengers with time-saving and safety benefits and in particular a reduction in the operator’s exposure to carcinogenic phenylenediamines