Mercuracarborand-catalyzed Diels-Alder reactions of a thionoester with cyclopentadiene

Inverse Electron-Demand Aza-Diels-Alder Reaction of α,β-Unsaturated Thioesters with In Situ-Generated 1,2-Diaza-1,3-dienes for the Synthesis of 1,3,4-Thiadiazines

A highly regioselective inverse electron-demand aza-Diels-Alder reaction of α,β-unsaturated thioesters with 1,2-diaza-1,3-dienes generated in situ from α-halogeno hydrazones was developed. With α,β-unsaturated thioesters as C═S dienophiles, the developed protocol enables the formation of diverse 3,6-dihydro-2H-1,3,4-thiadiazine derivatives in excellent yields. In the presence of lithium aluminum hydride, 3,6-dihydro-2H-1,3,4-thiadiazine derivatives could be further transformed into 5,6-dihydro-4H-1,3,4-thiadiazines in good yields.

(μ2-2-Meth-oxy-ethanol-κ(3) O (1):O (1),O (3))(2-meth-oxy-ethanol-κO (1))tris-(μ2-3,4,5,6-tetra-fluoro-o-phenyl-ene-κ(2) C (1):C (2))trimercury(II)

In the title compound, [Hg3(C6F4)3(C3H8O2)2], two O atoms from one 2-meth-oxy-ethanol ligand and one O atom from the second 2-meth-oxy-ethanol ligand coordinate three Hg(II) atoms [Hg-O = 2.765 (7)-2.890 (8) Å] in the trimeric organomercurial Lewis acid (o-C6F4Hg)3. The hy-droxy groups are involved in formation of intra- and inter-molecular O-H⋯O hydrogen bonds; the latter link two mol-ecules into centrosymmetric dimers. An extensive net of weak inter-molecular C-H⋯F inter-actions further consolidates the crystal packing.

Imidazolinium and amidinium salts as Lewis acid organocatalysts

The application of imidazolinium and amidinium salts as soft Lewis acid organocatalysts is described. These salts were suitable catalysts for the activation of unsaturated thioesters in a Diels-Alder reaction and in the ring opening of thiiranes and epoxides. The products were isolated in good yields. The mild catalysts did not cause desulfurization of the products containing a thiol or thiocarbonyl group.

On the Road to a Termolecular Complex with Acetone: A Heterometallic Supramolecular Network {[Rh2(O2CCF3)4]·μ2-OCMe2·[Cu4(O2CCF3)4]}

A novel heterometallic supramolecular network [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]](2)( infinity ) has been prepared by codeposition of the volatile mono(acetone) adduct [Rh(2)(O(2)CCF(3))(4).eta(1)-OCMe(2)](2) and copper(I) trifluoroacetate, [Cu(4)(O(2)CCF(3))(4)]. The product is of interest from the viewpoints of gas-phase supramolecular synthesis and a rare bridging coordination mode of acetone. It has been fully characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction. An X-ray structure revealed a layered 2D arrangement of the heterometallic [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]] units built by axial intermolecular interactions of the open electrophilic Rh(II) and Cu(I) centers and O-atoms of neighboring carboxylate groups. The coordination of the acetone molecules within the [[Rh(2)(O(2)CCF(3))(4)].micro(2)-OCMe(2).[Cu(4)(O(2)CCF(3))(4)]] unit is asymmetric with the Rh-O and Cu-O distances being 2.2173(15) and 2.7197(17) A, respectively. This work shows the potential of gas-phase deposition that may provide additional possibilities in supramolecular synthesis by utilizing intermolecular interactions and coordination bonds in a new way compared with conventional solution chemistry.

A Hydrogen-Bonded [(Mercuracarborand-Water)2 -Benzene] π-Sandwich Complex

Two cyclic Lewis acidic receptors, namely B-hexamethyl-9-mecuracarborand-3, [9,12-(CH3 )2 -C2 B10 H8 Hg]3 , each host a single water molecule. A benzene molecule is situated between the two complexed water molecules in a sandwich fashion that suggests there is O-H⋅⋅⋅π hydrogen bonding.

Crown compounds for anions: sandwich and half-sandwich complexes of cyclic trimetric perfluoro-o-phenylenemercury with polyhedral closo-[B10H10]2- and closo-[B12H12]2- anions

It has been shown by IR and NMR spectroscopy that cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4-Hg)3 (1) is capable of binding closo-[B10H10]2- and closo-[B12H12]2- anions to form complexes [[(o-C6F4Hg)3](B10-H10)]2- (2), [[(o-C6F4Hg)3]2(B10H10)]2-(3), [[(o-C6F4Hg)3](B12H12)]2- (4), and [[(o-C6F4Hg)3]2(B12H12)]2- (5). According to IR data, the bonding of the [B10H10]2- and [B12H12]2- ions to the macrocycle in these complexes is accomplished through the formation of B-H-Hg bridges. Complexes 2, 3, and 5 have been isolated in analytically pure form and have been characterized by spectroscopic means. X-ray diffraction studies of 3 and 5 have revealed that these compounds have unusual sandwich structures, in which the polyhedral di-anion is located between the planes of two molecules of 1 and is bonded to each of them through two types of B-H-Hg bridges. One type is the simultaneous coordination of a B-H group to all three Hg atoms of the macrocycle. The other type is the coordination of a B-H group to a single Hg atom of the cycle. According to X-ray diffraction data, complex 2 has an analogous but half-sandwich structure. The obtained complexes 2-5 are quite stable; their stability constants in THF/acetone (1:1) at 20 degrees C have been determined as 1.0 x 10(2)Lmol(-1), 2.6 x 10(3)L(2)mol(2), 0.7 x 10(2)Lmol(-1), and 0.98 x 10(3)L(2)mol(-2), respectively.