130422-35-4Relevant articles and documents
Total synthesis, relay synthesis, and structural confirmation of the C18-norditerpenoid alkaloid neofinaconitine
Shi, Yuan,Wilmot, Jeremy T.,Nordstrom, Lars Ulrik,Tan, Derek S.,Gin, David Y.
, p. 14313 - 14320 (2013)
The first total synthesis of the C18-norditerpenoid aconitine alkaloid neofinaconitine and relay syntheses of neofinaconitine and 9-deoxylappaconitine from condelphine are reported. A modular, convergent synthetic approach involves initial Diels-Alder cycloaddition between two unstable components, cyclopropene 10 and cyclopentadiene 11. A second Diels-Alder reaction features the first use of an azepinone dienophile (8), with high diastereofacial selectivity achieved via rational design of siloxydiene component 36 with a sterically demanding bromine substituent. Subsequent Mannich-type N-acyliminium and radical cyclizations provide complete hexacyclic skeleton 33 of the aconitine alkaloids. Key endgame transformations include the installation of the C8-hydroxyl group via conjugate addition of water to a putative strained bridghead enone intermediate 45 and one-carbon oxidative truncation of the C4 side chain to afford racemic neofinaconitine. Complete structural confirmation was provided by a concise relay synthesis of (+)-neofinaconitine and (+)-9-deoxylappaconitine from condelphine, with X-ray crystallographic analysis of the former clarifying the NMR spectral discrepancy between neofinaconitine and delphicrispuline, which were previously assigned identical structures.
Incorporation of primary amines into a polyester chain by a combination of chemical and lipase-catalyzed ε-caprolactone ring-opening processes
Marzorati, Mattia,Hult, Karl,Riva, Sergio,Danieli, Bruno
, p. 1963 - 1968 (2007)
A simple chemoenzymatic strategy for the incorporation of bioactive and suitably functionalized molecules into a polyester chain has been developed. The protocol involves first the reaction of a primary amine with ε-caprolactone to give an amide carrying a terminal primary hydroxy group, followed by the enzymatic growth of the polymeric chain triggered by Novozym 435. This method is versatile and easy to handle and is suitable for the incorporationof different amines into polyesters, as has been shown with the model compounds benzylamine and tryptamine, the bioactive compound N-deacetylthiocolchicine and the functionalized propargylamine and tyramine .
Temporal separation of catalytic activities allows anti-Markovnikov reductive functionalization of terminal alkynes
Li, Le,Herzon, Seth B.
, p. 22 - 27 (2014/01/17)
There is currently great interest in the development of multistep catalytic processes in which one or several catalysts act sequentially to rapidly build complex molecular structures. Many enzymes - often the inspiration for new synthetic transformations - are capable of processing a single substrate through a chain of discrete, mechanistically distinct catalytic steps. Here, we describe an approach to emulate the efficiency of these natural reaction cascades within a synthetic catalyst by the temporal separation of catalytic activities. In this approach, a single catalyst exhibits multiple catalytic activities sequentially, allowing for the efficient processing of a substrate through a cascade pathway. Application of this design strategy has led to the development of a method to effect the anti-Markovnikov (linear-selective) reductive functionalization of terminal alkynes. The strategy of temporal separation may facilitate the development of other efficient synthetic reaction cascades.
