Three-dimensional (3D) chemical models
are a well-established learning
tool used to enhance the understanding of chemical structures by converting
two-dimensional paper or screen outputs into realistic three-dimensional
objects. While commercial atom model kits are readily available, there
is a surprising lack of large molecular and orbital models that could
be used in large spaces. As part of a program investigating the utility
of 3D printing in teaching, a modular size-adjustable molecular model
and orbital kit was developed and produced using 3D printing and was
used to enhance the teaching of stereochemistry, isomerism, hybridization,
and orbitals.
3D printing has the potential to transform the way in which chemical reactions are carried out due to its low-cost, ease-of-use as a technology and its capacity to expedite the development of iteratively enhanced prototypes. In this present study, we developed a novel, low-cost polypropylene (PP) column reactor that was incorporated into an existing continuousflow reactor for the synthesis of heterocycles. The utility and
Three peri-substituted trisulfide-2-oxides are prepared by treatment of 1,8-naphthalene dithiols with thionyl chloride and pyridine. The 1,2,3-trithiane-2-oxide ring adopts a sofa conformation in the solid state, with a pseudoaxial oxygen and evidence of ring strain (peri-interaction). Heating the trisulfide-2-oxides in the presence of a diene results in formal sulfur monoxide (SO) transfer to form unsaturated cyclic sulfoxides, along with a recyclable 1,8-naphthalene disulfide. The presence of o-methoxy or o-tert-butyl substituents on the naphthalene ring lowers the temperature and increases the rate at which SO transfer occurs. Trapping experiments and kinetic studies are consistent with the generation of triplet SO, followed by in situ trapping by diene. Transfer of SO also occurs upon irradiation at room temperature, but yields of sulfoxide are lower. Dehydration of the sulfoxides under Pummerer conditions gives thiophenes, including the naturally occurring thioperillene. Two dienes form thiophenes directly under the SO transfer conditions. The methodology is applied in a formal synthesis of the antiplatelet medication Plavix.
Bulking up: The thermal barrier to rearrangement of a vic-disulfoxide is significantly increased through steric buttressing about the (O)S--S(O) bond. Whereas the title compounds represent the most thermally stable vic-disulfoxides known to date, they also undergo a novel photomediated epimerization at room temperature (see scheme).
A novel common precursor approach towards both tricyclic and spirocyclic heterocycles is described. Cyclisations are based on thiyl radical/ isocyanide methodology and avoid the use of tin.Tricyclic heterocycles and their related spirocyclic congeners are attractive synthetic targets due to their occurrence in natural products and their frequent use as therapeutics.
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