Cyclopropenium Salts as Cyclable, High‐Potential Catholytes in Nonaqueous Media

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136488/1/aenm201602027-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136488/2/aenm201602027.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136488/3/aenm201602027_am.pd

Closed Aromatic Tubes-Capsularenes

In this study, we describe a synthetic method for incorporating arenes into closed tubes that we name capsularenes. First, we prepared vase-shaped molecular baskets 4–7. The baskets comprise a benzene base fused to three bicycle[2.2.1]heptane rings that extend into phthalimide (4), naphthalimide (6), and anthraceneimide sides (7), each carrying a dimethoxyethane acetal group. In the presence of catalytic trifluoroacetic acid (TFA), the acetals at top of 4, 6 and 7 change into aliphatic aldehydes followed by their intramolecular cyclization into 1,3,5-trioxane (1H NMR spectroscopy). Such ring closure is nearly a quantitative process that furnishes differently sized capsularenes 1 (0.7×0.9 nm), 8 (0.7×1.1 nm;) and 9 (0.7×1.4 nm;) characterized by X-Ray crystallography, microcrystal electron diffraction, UV/Vis, fluorescence, cyclic voltammetry, and thermogravimetry. With exceptional rigidity, unique topology, great thermal stability, and perhaps tuneable optoelectronic characteristics, capsularenes hold promise for the construction of novel organic electronic devices

Iridium-Catalyzed Oxidative Olefination of Furans with Unactivated Alkenes

The oxidative coupling of arenes and alkenes is an attractive strategy for the synthesis of vinylarenes, but reactions with unactivated alkenes have typically occurred in low yield. We report an Ir-catalyzed oxidative coupling of furans with unactivated olefins to generate branched vinylfuran products in high yields and with high selectivities with a second alkene as the hydrogen acceptor. Detailed mechanistic experiments revealed catalyst decomposition pathways that were alleviated by the judicious selection of reaction conditions and application of new ligands

Iridium-Catalyzed, Intermolecular Hydroetherification of Unactivated Aliphatic Alkenes with Phenols

Metal-catalyzed addition of an O–H bond to an alkene is a desirable process because it allows for rapid access to ethers from abundant starting materials without the formation of waste, without rearrangements, and with the possibility to control the stereoselectivity. We report the intermolecular, metal-catalyzed addition of phenols to unactivated α-olefins. Mechanistic studies of this rare catalytic reaction revealed a dynamic mixture of resting states that undergo O–H bond oxidative addition and subsequent olefin insertion to form ether products

Iridium-Catalyzed Intermolecular Asymmetric Hydroheteroarylation of Bicycloalkenes

Catalytic hydroarylation of alkenes is a desirable process because it can occur under neutral conditions with regioselectivity complementary to that of acid-catalyzed reactions and stereoselectivity derived from the catalyst. We report an intermolecular asymmetric addition of the C–H bonds of indoles, thiophenes, pyrroles, and furans to bicycloalkenes in high yield with high enantiomeric excess. These heteroarene alkylations occur ortho to the heteroatom. This selectivity is observed even with unprotected indoles, which typically undergo alkylation at the C3 position. Initial mechanistic studies revealed that oxidative addition of a heteroarene C–H bond to a neutral Ir^I species occurs within minutes at room temperature and occurs in the catalytic cycle prior to the turnover-limiting step. Products from syn addition of the C–H bond across the olefin were observed

Iridium-Catalyzed Intermolecular Asymmetric Hydroheteroarylation of Bicycloalkenes

Catalytic hydroarylation of alkenes is a desirable process because it can occur under neutral conditions with regioselectivity complementary to that of acid-catalyzed reactions and stereoselectivity derived from the catalyst. We report an intermolecular asymmetric addition of the C–H bonds of indoles, thiophenes, pyrroles, and furans to bicycloalkenes in high yield with high enantiomeric excess. These heteroarene alkylations occur ortho to the heteroatom. This selectivity is observed even with unprotected indoles, which typically undergo alkylation at the C3 position. Initial mechanistic studies revealed that oxidative addition of a heteroarene C–H bond to a neutral Ir^I species occurs within minutes at room temperature and occurs in the catalytic cycle prior to the turnover-limiting step. Products from syn addition of the C–H bond across the olefin were observed