ABSTRACT
The total synthesis of soraphen A, a myxobacterial metabolite and inhibitor of acetyl CoA carboxylase, was completed in 11 steps (longest linear sequence), less than half the steps previously required. Seven metal-catalyzed processes were deployed to unlock step-economy (comprising five asymmetric processes and four C-C bond formations). The present route does not utilize chiral auxiliaries, and four of five C-C bond formations exploit non-premetalated partners. To maximize convergency, an asymmetric Tsuji reduction was developed using a Pd-AntPhos catalyst that allows a metathesis-inactive allylic carbonate to serve as a masked terminal olefin, thereby enabling successive olefin metathesis events.
Subject(s)
Alkenes/chemistry , Enzyme Inhibitors/chemical synthesis , Macrolides/chemical synthesis , Acetyl-CoA Carboxylase/antagonists & inhibitors , Acetyl-CoA Carboxylase/metabolism , Carbon/chemistry , Catalysis , Crystallography, X-Ray , Enzyme Inhibitors/chemistry , Macrolides/chemistry , Molecular Conformation , Oxidation-Reduction , Palladium/chemistry , StereoisomerismABSTRACT
Direct conversion of aldehydes to ketones is achieved via rhodium-catalyzed vinyl triflate-aldehyde reductive coupling-redox isomerization mediated by potassium formate. This method circumvents premetalated C-nucleophiles and discrete redox manipulations typically required to form ketones from aldehydes.
ABSTRACT
Cyclometallated π-allyliridium C,O-benzoates modified with (S)-tol-BINAP, which are stable to air, water, and SiO2 , catalyze highly enantioselective N-allylations of indoles and related azoles. This reaction complements previously reported metal-catalyzed indole allylations in that complete levels of N versus C3 and branched versus linear regioselectivity are observed.
Subject(s)
Acetates/chemistry , Allyl Compounds/chemistry , Azoles/chemistry , Indoles/chemistry , Iridium/chemistry , Alkylation , Catalysis , StereoisomerismABSTRACT
The preparation of substituted azaindolines utilizing a domino palladium-catalyzed Heck cyclization/Suzuki coupling is described. The approach is amenable for the construction of all four azaindoline isomers. A range of functional groups such as esters, amides, ketones, sulfones, amines, and nitriles are all tolerated under the reaction conditions.
ABSTRACT
Microbial degradation of clothianidin was characterized under aerobic and anaerobic California rice field conditions. Rate constants (k) and half-lives (DT50) were determined for aerobic and anaerobic microcosms, and an enrichment experiment was performed at various nutrient conditions and pesticide concentrations. Temperature effects on anaerobic degradation rates were determined at 22 ± 2 and 35 ± 2 °C. Microbial growth was assessed in the presence of various pesticide concentrations, and distinct colonies were isolated and identified. Slow aerobic degradation was observed, but anaerobic degradation occurred rapidly at both 25 and 35 °C. Transformation rates and DT50 values in flooded soil at 35 ± 2 °C (k = -7.16 × 10(-2) ± 3.08 × 10(-3) day(-1), DT50 = 9.7 days) were significantly faster than in 25 ± 2 °C microcosms (k= -2.45 × 10(-2) ± 1.59 × 10(-3) day(-1), DT50 = 28.3 days). At the field scale, biodegradation of clothianidin will vary with extent of oxygenation.
