Studies of microwave-enhanced Suzuki-Miyaura vinylation of electron-rich sterically hindered substrates utilizing potassium vinyltrifluoroborate.

The Suzuki-Miyaura cross-coupling of sterically hindered and electron-rich ortho,ortho'-substituted aryl halides with potassium vinyltrifluoroborate utilizing microwave irradiation has been conducted while adjusting solvent ratio, irradiation time, and catalyst loading to find optimal conditions. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate leads to a mixture of the desired styrene derivative, and the reduced product. 4-Bromo-1,3,5-trimethoxybenzene, methyl 4-bromo-3,5-dimethoxybenzoate, and mesitylene bromide were also coupled to test the breadth and scope of this methodology.

Preparation, structures and preliminary host-guest studies of fluorinated syn-bis-quinoxaline molecular tweezers.

A series of polycyclic frameworks with fluorinated syn-facial quinoxaline sidewalls has been prepared as potential molecular tweezers for electron-rich guest compounds. Our synthetic route to the cyclooctadiene-derived scaffolds 16a-d takes advantage of the facile isolation of a novel spirocyclic precursor 9b with the crucial syn-orientation of its two alkene moieties. The crystal structure of 16c displays two features typical of a molecular tweezer: inclusion of a solvent molecule in the molecular cleft and self-association of the self-complementary scaffolds.

anti-1',6',7',8',9',14',15',16'-Octa-chloro-dispiro-[1,3-dioxolane-2,17'-penta-cyclo-[12.2.1.1.0.0]octa-decane-18',2''-1,3-dioxolane]-7',15'-diene.

The title compound, C(22)H(20)Cl(8)O(4), was prepared as part of the synthesis of precursors for the preparation of fluorinated mol-ecular tweezers. The mol-ecule sits on an inversion center, thus requiring that the cyclo-octane ring adopt a chair conformation.

Reduced hippocampal functional connectivity in Alzheimer disease.

Objective: To determine if functional connectivity of the hippocampus is reduced in patients with Alzheimer disease.

Design: Functional connectivity magnetic resonance imaging was used to investigate coherence in the magnetic resonance signal between the hippocampus and all other regions of the brain.

Participants: Eight patients with probable Alzheimer disease and 8 healthy volunteers.