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Cascade reactions are often key steps in the efficient total synthesis of complex natural products. The key step in Heathcock's synthesis of dihydroprotodaphniphylline features a highly efficient cascade involving two aldehyde/amine condensations, a Prins-like cyclization, and a 1,5-hydride transfer to afford a pentacyclic structure from an acyclic starting material.
A biochemical cascade, also known as a signaling cascade or signaling pathway, is a series of chemical reactions that occur within a biological cell when initiated by a stimulus.
Substrates containing multiple adjacent hydroxyl groups may undergo "cascade" epoxide migrations with inversion at each site of nucleophilic attack. In one example, inversion of three contiguous stereocenters results after two epoxide migrations, opening of the epoxide by carboxylate, and hydrolysis of the resulting lactone.
Nazarov cyclization cationic cascade. Enolate trapping with various electrophiles is decidedly less common. In one study, the Nazarov cyclization is paired with a Michael reaction using an iridium catalyst to initiate nucleophilic conjugate addition of the enolate to β-nitrostyrene.
The zwitterionic enolate produced upon addition of nucleophilic catalyst to the enone adds to an aldehyde carbonyl to generate an alkoxide. This alkoxide undergoes a subsequent 1,3-Brook rearrangement and elimination cascade to afford a siloxy-methylene enone and release the catalyst.
In the field of molecular biology, the cAMP-dependent pathway, also known as the adenylyl cyclase pathway, is a G protein-coupled receptor-triggered signaling cascade used in cell communication. [ 1 ]
The Stetter reaction is a reaction used in organic chemistry to form carbon-carbon bonds through a 1,4-addition reaction utilizing a nucleophilic catalyst. [1] While the related 1,2-addition reaction, the benzoin condensation, was known since the 1830s, the Stetter reaction was not reported until 1973 by Dr. Hermann Stetter. [2]
The diazo compound then does a nucleophilic attack on the carbonyl-containing compound (nucleophilic addition), producing a tetrahedral intermediate (2). This intermediate decomposes by the evolution of nitrogen gas forming the tertiary carbocation intermediate (3). Initial steps in the Buchner–Curtius–Schlotterbeck reaction mechanism