Sulfamate-Tethered <i>Aza</i>-Wacker Cyclization Strategy for the Syntheses of 2‑Amino-2-deoxyhexoses: Preparation of Orthogonally Protected d‑Galactosamines

We present a new strategy for the assembly of protected d-galactosamine synthons. Our route uses a sulfamate-tethered aza-Wacker cyclization as a key step and commences from d-erythrono-1,4-lactone. This stands in contrast to most literature syntheses of 2-amino-2-deoxyhexose derivatives, as these generally employ glycals or hexoses as starting materials. This strategy may serve as a template for the assembly of many other 2-amino-2-deoxyhexoses with protection patterns difficult to access by conventional methods

<i>in,in</i>-Cyclophanes with Bridgehead Methyl Groups

Two <i>in,in</i>-cyclophanes that contain methyl groups in their central cavities have been synthesized, and their X-ray structures have been determined. One of these molecules contains a very short nonbonded contact between a hydrogen atom and a methyl group, and the other is the first example of a macrobicyclic compound that contains two inwardly directed methyl groups

Synthesis and Chiroptical Properties of Arylimines of Cholest-4-ene-3,6-dione

In the hope of generating a new class of materials with large optical rotations, various arylamines were condensed with cholest-4-ene-3,6-dione (<b>2</b>) to give 3-arylimino steroids. These compounds possess moderately high specific rotations ([α]_D ∼300–800) and strong circular dichroism. One such derivative, 3-(4-methoxyphenylimino)­cholest-4-en-6-one (<b>3</b>), crystallizes as the (<i>E</i>)-imine and upon dissolution undergoes mutarotation to an equilibrium mixture of (<i>E</i>)- and (<i>Z</i>)-isomers with a half-life of approximately 1 h at room temperature, as judged by both NMR spectroscopy and polarimetry

Synthesis and Chiroptical Properties of Arylimines of Cholest-4-ene-3,6-dione

In the hope of generating a new class of materials with large optical rotations, various arylamines were condensed with cholest-4-ene-3,6-dione (<b>2</b>) to give 3-arylimino steroids. These compounds possess moderately high specific rotations ([α]_D ∼300–800) and strong circular dichroism. One such derivative, 3-(4-methoxyphenylimino)­cholest-4-en-6-one (<b>3</b>), crystallizes as the (<i>E</i>)-imine and upon dissolution undergoes mutarotation to an equilibrium mixture of (<i>E</i>)- and (<i>Z</i>)-isomers with a half-life of approximately 1 h at room temperature, as judged by both NMR spectroscopy and polarimetry

Synthesis and Chiroptical Properties of Arylimines of Cholest-4-ene-3,6-dione

In the hope of generating a new class of materials with large optical rotations, various arylamines were condensed with cholest-4-ene-3,6-dione (<b>2</b>) to give 3-arylimino steroids. These compounds possess moderately high specific rotations ([α]_D ∼300–800) and strong circular dichroism. One such derivative, 3-(4-methoxyphenylimino)­cholest-4-en-6-one (<b>3</b>), crystallizes as the (<i>E</i>)-imine and upon dissolution undergoes mutarotation to an equilibrium mixture of (<i>E</i>)- and (<i>Z</i>)-isomers with a half-life of approximately 1 h at room temperature, as judged by both NMR spectroscopy and polarimetry

Tribenzodecacyclene and Hexabenzodecacyclene

High-temperature, TiCl₄-catalyzed, triple aldol condensations of aceanthrenone <b>5</b> and acenaphthacenone <b>6</b> gave tribenzodecacyclene <b>3</b> and hexabenzodecacyclene <b>4</b>, respectively, in yields of 16 and 0.8%, respectively. Compound <b>3</b> is a red, crystalline solid that is stable under ordinary conditions; its X-ray structure reveals it to be a strongly pitched, <i>C</i>₃-symmetric, molecular propeller. In contrast, the more highly strained compound <b>4</b> is a blue-black solid whose solutions are unstable to air and light. Its simple NMR spectra, as well as HDFT calculations, indicate that it is a <i>D</i>₃-symmetric molecular propeller

An <i>in-</i>Triphenylaminophane

The synthesis and characterization of the triphenylamine-capped cyclophane <b>3</b> are described. It proved to be a conformationally rigid molecular propeller, with an inwardly pyramidalized, unreactive amine

Self-Assembled Cyclophane-Type Copper(I) Complexes of 2,4,6-Tris(diphenylphosphino)-1,3,5-triazine and Their Catalytic Application

The triazine-based trisphosphine, 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine (<b>1</b>) was prepared in improved yield by reacting cyanuric chloride with 3 equiv of trimethylsilyldiphenylphosphine. The solid-state structure of <b>1</b> showed short intermolecular P···P contacts of 3.362 Å, which is significantly shorter than the sum of the van der Waals radii of phosphorus atoms (3.6 Å). The reaction of 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine (<b>1</b>) with copper­(I) salts in a 2:3 molar ratio yielded various cyclophane-type complexes in quantitative yield. The solid-state structures of these clusters have been found to depend on the size of the halide ions, the solvent employed, and the reaction conditions. Copper­(I) chloride formed a monomeric metallocyclophane, whereas copper­(I) bromide and copper­(I) iodide derivatives preferred dimeric and 1D-polymeric structures, respectively. The tricationic complexes derived from Cu^I ion and 2,4,6-tris­(diphenyl­phosphino)-1,3,5-triazine also adopted monomeric metallocyclophane structures. These complexes have been employed in the A³ coupling reaction under microwave irradiation. The copper­(I) iodide derivative showed excellent catalytic efficiency

Synthesis and Structures of Cuprous Triptycylthiolate Complexes

A synthesis of 1-(thioacetyl)­triptycene (<b>5</b>), a convenient protected form of 1-(thiolato)­triptycene [STrip]⁻, is described, a key transformation being the high yield conversion of <i>tert</i>-butyl 1-triptycenyl sulfide (<b>8</b>) to <b>5</b> by a protocol employing BBr₃/AcCl. Syntheses of the two-coordinate copper­(I) compounds [Bu₄N]­[Cu­(STrip)₂], [Bu₄N]<b>10</b>, and [(Cu­(IMes)­(STrip)] (<b>13</b>) proceed readily by chloride displacement from CuCl and [Cu­(IMes)­Cl], respectively. Reaction of <b>10</b> with Ph₃SiSH or Me₃SiI produces the heteroleptic species [Cu­(STrip)­(SSiPh₃)]⁻ (<b>11</b>) and [Cu­(STrip)­I]⁻ (<b>12)</b>, detected by mass spectrometry, in mixture with the homoleptic bis­(thiolate) anions. Structural identification by X-ray crystallography of the ligand precursor molecules 9-(thioacetyl)­anthracene (<b>4</b>, triclinic and orthorhombic polymorphs), <i>tert</i>-butyl 9-anthracenyl sulfide (<b>7</b>), <b>5</b>, and <i>tert</i>-butyl 1-triptycenyl sulfide (<b>8</b>) are presented. Crystallographic characterization of bis­(9-anthracenyl)­sulfide (<b>3</b>), which features a C–S–C angle of 104.0° and twist angle of 54.8° between anthracenyl planes, is also given. A crystal structure of [Bu₄N]­[(STrip)], [Bu₄N]<b>9</b>, provides an experimental measure of 144.6° for the ligand cone angle. The crystal structures of [Bu₄N]<b>10</b> and <b>13</b> are reported, the former of which reveals an unexpectedly small C–S···S–C torsion angle of ∼41° (average of two values), which confers a near “cis” disposition of the triptycenyl groups with respect the S–Cu–S axis. This conformation is governed by interligand π···π and CH···π interactions. A crystal structure of an adventitious product, [Bu₄N]­[(Cu-STrip)₆(μ₆-Br)]·[Bu₄N]­[PF₆], [Bu₄N]<b>14</b>·[Bu₄N]­[PF₆] is described, which reveals a cyclic hexameric structure previously unobserved in cuprous thiolate chemistry. The Cu₆S₆ ring displays a centrosymmetric cyclohexane chair type conformation with a Br^– ion residing at the inversion center and held in place by apparent soft–soft interactions with the Cu­(I) ions

Exceptional Steric Congestion in an <i>in</i>,<i>in</i>-Bis(hydrosilane)

The synthesis and characterization of a macrobicyclic <i>in</i>,<i>in</i>-bis­(hydrosilane) is described. A combination of crystallographic and computational data indicate that the central hydrogen–hydrogen nonbonded contact distance is the shortest for any crystallographically characterized compound