Abstract:We report the synthesis of phenylalanine-derived trifluoromethyl ketones for the in situ generation of dioxiranes for the purpose of oxidation catalysis. The key features of this synthesis include the use of a masked ketone strategy and a Negishi cross -coupling to access the parent amino acid. The derivatives can be readily incorporated into a peptide for use in oxidation chemistry and exhibit good stability and reactivity.
“…Spectroscopic data are in agreement with those reported in the literature. [50] Methyl 3-(1,2,3,6,7,8-Hexahydropyren-4-yl)-2methylpropanoate (7). A solution of iodide 4 (240 mg, 1.05 mmol) in dry toluene/DMA (15 : 1, 4.3 ml) was added to ZnÀ Cu couple (126 mg) under a N 2 atmosphere.…”
The aromatic core of an overcrowded alkene‐based molecular motor is extended with the goal of inducing isomerization with visible light instead of harmful UV light. In our design, the common naphthalene moiety in the upper half of the motor is changed to pyrene. The photochemical and thermal isomerization processes are studied in detail using DFT calculations as well as NMR and UV/VIS spectroscopy. Our studies confirm that extension of the π‐system of the upper half successfully leads to a shift of the excitation wavelength into the visible region, while retaining proper rotary function.
“…Spectroscopic data are in agreement with those reported in the literature. [50] Methyl 3-(1,2,3,6,7,8-Hexahydropyren-4-yl)-2methylpropanoate (7). A solution of iodide 4 (240 mg, 1.05 mmol) in dry toluene/DMA (15 : 1, 4.3 ml) was added to ZnÀ Cu couple (126 mg) under a N 2 atmosphere.…”
The aromatic core of an overcrowded alkene‐based molecular motor is extended with the goal of inducing isomerization with visible light instead of harmful UV light. In our design, the common naphthalene moiety in the upper half of the motor is changed to pyrene. The photochemical and thermal isomerization processes are studied in detail using DFT calculations as well as NMR and UV/VIS spectroscopy. Our studies confirm that extension of the π‐system of the upper half successfully leads to a shift of the excitation wavelength into the visible region, while retaining proper rotary function.
“…This highly modular approach has been exploited by other researchers to access a range of fluorinated motifs [ 32 , 33 ]. For example, Featherston and Miller employed a Negishi coupling strategy to access the multiple-fluorine containing amino acid 7 [ 34 ]. Starting from an iodo-serine derivative ( 5 ) and a bromoaromatic coupling partner ( 6 ), Negishi cross-coupling was carried out to access amino acid 7 in 54 % yield ( Scheme 3 ).…”
“…This amino acid was employed as a critical building block in the synthesis of a peptide-based oxidation catalyst. Scheme 3 A fluorinated amino acid used in the synthesis of an oxidation catalyst, Featherston and Miller [ 34 ]. …”
“…The synthesis of trifluoromethyl appended aromatic amino acids were reported by Featherston and Miller (Scheme 11). 44 Cross-coupling was successfully carried out between Cbzprotected iodide 23 and a fluoro-aromatic to give 24 in a 54% yield. The aromatic amino acid 24 was then successfully transformed into the corresponding ketone through treatment with ozone.…”
Section: Synthesis Of Aromatic Amino Acidsmentioning
The Negishi cross-coupling is a powerful C-C bond-forming reaction widely utilised in many areas of organic synthesis. This review details the use of Negishi cross-couplings in the synthesis of unnatural amino acids. The application of this reaction in the preparation of aromatic, heteroaromatic, and, complex amino acid derivatives are reviewed and presented herein.
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