Over the past decade, the integration of synthetic chemistry with flow processing has resulted in a powerful platform for molecular assembly that is making an impact throughout the chemical community. Herein, we demonstrate the extension of these tools to encompass complex natural product synthesis. We have developed a number of novel flow-through processes for reactions commonly encountered in natural product synthesis programs to achieve the first total synthesis of spirodienal A and the preparation of spirangien A methyl ester. Highlights of the synthetic route include an iridium-catalyzed hydrogenation, iterative Roush crotylations, gold-catalyzed spiroketalization and a late-stage cis-selective reduction.

In this update, the asymmetric homogeneous hydrogenation of a number of trisubstituted olefins utilizing the recently developed tube‐in‐tube gas‐liquid flow reactor is described. A number of chiral iridium‐ and rhodium‐based catalysts and other parameters such as pressure, solvent, temperature and catalyst loading were screened. The advantage of the flow set‐up for rapid screening and optimization of reaction parameters is illustrated. Furthermore, a comparative study using batch conditions aided in the optimization of the flow reaction set‐up. The set‐up was further modified to recycle the catalyst which prolonged catalytic activity.

Over the past decade, the integration of synthetic chemistry with flow processing has resulted in a powerful platform for molecular assembly that is making an impact throughout the chemical community. Herein, we demonstrate the extension of these tools to encompass complex natural product synthesis. We have developed a number of novel flow‐through processes for reactions commonly encountered in natural product synthesis programs to achieve the first total synthesis of spirodienal A and the preparation of spirangien A methyl ester. Highlights of the synthetic route include an iridium‐catalyzed hydrogenation, iterative Roush crotylations, gold‐catalyzed spiroketalization and a late‐stage cis‐selective reduction.

We have studied, by 'micro-magneto-photoluminescence', the eigenstates of excitons localised in the interfacial potential of narrow GaAs=Al 0:31 Ga 0:69 As quantum wells. These behave in many respects as quantum dot excitons, and give narrow emission lines that permit direct resolution of Zeeman splittings. Some dots show small zero-field splitting (< 100 meV), varying down to below the limit of resolution of our technique (% 25 meV). For these dots the excitonic g-factor depends on well-width, and also shows variation with the applied field B. The variation with B is related to the band mixing which is more prominent in these weakly-confined dots than in, for example, typical Stranski-Krastanow dots. The magnitude of the term linear in B can be calculated in a simplified model of the confined state, which gives a method of estimating the lateral extent of the confining potential. For particular transitions which are found at the extreme low-energy end of the emission from wells of 2 nm and 3 nm width, a different behaviour is found. These show much larger zero-field splitting of around 1 meV, and much smaller diamagnetic shift than that in the more usual dots with small zero-field splitting. The measured spin fine structure of these states is compared with that calculated from a spin Hamiltonian for a heavy-hole exciton, which gives a unique determination of the full three-dimensional g-factor for a single quantum dot.

A route to enantiopure (R)-(+)-3-methyl-6-isopropenyl-cyclohept-3-enone-1, an intermediate for terpenoids, has been developed and includes a highly chemo- and regioselective Tiffeneau-Demjanov reaction. Starting from readily available (R)-(-)-carvone, this robust sequence is available on a deca-gram scale and uses flow chemistry for the initial epoxidation reaction. The stereochemistry of the addition of two nucleophiles to the carbonyl group of (R)-(-)-carvone has been determined by X-ray diffraction studies and chemical correlation.

Significance: Merobatzelladine B was isolated in 2009 from the marine sponge Monanchora sp. by Matsunaga and co-workers. It exhibits moderate antimicrobial activity and inhibitory effects against a strain of Plasmodium falciparum. It possesses a fused tricyclic guanidine core and two n-pentyl chains that are positioned anti to one another.Comment: This synthesis utilizes iterative stereoand regioselective palladium-catalyzed carboamination reactions to build two of the three fused heterocycles in good yield and excellent diastereoselectivity. The selectivity of the second carboamination step is attributed to the preferred boat-like transition structure K, which minimizes steric hindrance with the previously formed pyrrolidine ring and the metal center.

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Total Synthesis of (+)-Ambuic Acid: α-Bromination with 1,2-Dibromotetrachloroethane