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The marine red algae of Laurencia species produce a dazzling array of halogenated natural products using halide from seawater. In 2006 we proposed a novel  for the Obtusallene family of natural products via electrophilic bromination,¹ and followed this up shortly thereafter with a  of the tetrahydrofuran core of obtusallenes II and IV.² The biogenesis suggested that some structural reassignments of the family were required, which were consistent with subsequent .³ Subsequent bromonium ion induced transannular oxonium ion formation-fragementations in  led to the structural reassignment of obtusallenes V-VII.⁴ In 2016, this work  in the total synthesis of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C and marilzabicycloallene D.⁵ Notable outcomes from this project include  the stereochemical course of bromoetherifcation of enynes,⁶ the prediction of the existence of the marilzabicycloallenes prior to their , and the use of halogen-induced isotopic 13C NMR shifts for the identification of halogen bearing carbons.⁴ Further, we have also shown that epoxidation of bromoallenes connects red algae metabolites by an ,⁷ which led to the the first stable and .⁸ Notably, the latter paper reports the first X-ray crystal structure of any allene oxide. In turn, this chemistry led us to discover a  with contributions from attractive dispersion force control.⁹

In a related project we have reported a  for the halogenated medium ring ethers from Laurencia and experimental corroboration with a model epoxide,¹⁰ building on  based on intramolecular bromonium ion assisted epoxide ring-opening,¹¹ and have reported a proof-of-principle  of a linear C15-precursor to a dibrominated bicyclic medium ring ether relevant to Laurencia species.¹²

We have targeted other halogenated natural products from marine sources, and have reported a three step  of myrcene as an approach to halomon,¹³ the ¹⁴ - and subsequently ¹⁵ - synthesis, of polysiphenol (and halologues) by highly regioselective intramolecular oxidative coupling, and the use of an iterative relay cross metathesis method for the  of a diterpene-benzoate macrolide of biogenetic relevance to the bromophycolides.¹⁶

Work in the group continues in the area.

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