The epoxide deoxygenation reaction is formally the reverse of theepoxidation reaction. Compared to epoxidation, which has reached its fullmaturity, epoxide deoxygenation has not been as intensively developed.Among the few deoxygenation reagents, a handful are catalytic in a metalcomplex, show high stereospecificity and operate under mild conditions. Acommon feature of all...
Enantioselective epoxidation of crotyl alcohol, followed
by a cuprate mediated methylation, gave a 1:1 mixture of
(2S) -3- methyl -1,2- butanediol and (2R,3S)-2-methy1-1,3-
butanediol. The latter was separated as its 2,4,6-trimethylbenzenesulfonate
derivative and converted via the
iodide to the corresponding phosphonium salt. The separated
butanediol derivatives were independently transformed
to...
Bromoalkoxylation of dihydropyran with bromine and 1-borneol, followed by dehydrobromination and epoxidation, afforded trans-2-1- bornyloxy-3,4-epoxytetrahydropyran as a major product. This was treated with sodium phenylselenide to give a 1:1 mixture of (2R,3R,4R)- 2-1-bornyloxy-3-hydroxy-4-phenylselenotetrahydropyran and its (2S,3S, 4S) diastereomer. Elimination of the selenoxide, derived from oxidation of the former with hydrogen...
Since the discovery of molecular chirality in 1848, this notion has had a substantial impact on medicine, biology, and chemistry. Extensive effort has been directed towards the construction of chiral molecules that contain sp³ hybridized stereogenic centers. In contrast, less effort has been dedicated to molecules that are chiral by...
A great variety of topologically protected defects exist in ordinary and exotic states of matter. Some of them are promising candidates for technological applications such as magnetic memory or quantum computers. Others possess some properties of elementary particles that could lead to potential applications in quantum fields. Nematic liquid crystals...
Many D2d-symmetric 2,2',6,6'-tetrasubstituted biphenyls are
readily prepared via net oxidative dimerization of appropriate
1,3-disubstituted benzenes. Conversion of such proprochiral
compounds to useful C2-symmetric chiral biphenyls requires
formal replacement of two substituents on opposing aryl ring
units with alternate groups. This under exploited
desymmetrization tactic has been demonstrated for the
generation...
In Part I, (4S,5R)-4,5-dimethyl-4-phenylcyclohex-2-enone (19a) was prepared in 73% yield with high enantio- and diastereo-selectivity (er > 98:2, dr > 20:1) on a multigram scale by a Yamada-Otani condensation between (E)-pent-3-en-2-one and 2-phenylpropanal catalyzed by a sulfonimide derivative of (S)-proline (18, HuaCat®). Synthetically useful transformations of the cyclohexenone product 19a...
Suspended metallic carbon nanotubes (m-CNTs) exhibit a remarkably large transport gap that can exceed 100 meV. Both experiment and theory suggest that strong electron-electron interactions play a crucial role in generating this electronic structure. To further understand this strongly-interacting system, we have performed electronic measurements of suspended m-CNTs with known...