Yoshio Kabe

NATURE OF PEROXY INTERMEDIATES PRODUCER BY THE PHOTOSENSITIZED OXYGENATION OF DIETHYL SULFIDE AND PHENYLBENZOYL DIAZOMETHANE: KINETIC STUDIES BY CO‐OXIDATION WITH 4‐MONO SUBSTITUTED DIPHENYL SULFIDES

Abstract— Competitive oxidations of pairs of 4‐monosubstituted diphenyl sulfides by intermediates produced in the photosensitized oxygenation of diethyl sulfide and phenylbenzoyl diazomethane were carried out in methanol and benzene, respectively. Relative rates of oxidation correlate well with Ham‐metts a, and p values of ‐0.61 (oxidation in the presence of diethyl sulfide) and ‐0.32 (oxidation in the presence of phenylbenzoyl diazomethane) show that the diphenyl sulfides oxidizing intermediates have electrophilic character. In the photosensitized oxygenation of sulfides and diazo compounds, peroxy intermediates (a persulfoxide and a carbonyl oxide, respectively) have been proposed as the most probable intermediates.

Cyclotrigermanes. Synthesis and thermal decomposition

Abstract The reactions of dihalogenogermanes R 2 GeX 2 (X = halogen) with Mg and MgBr 2 in tetrahydrofuran produce the corresponding cyclotrigermanes (R 2 Ge) 3 , and cyclotetragermanes (R 2 Ge) 4 ; the preferred ring size of the products depends on the substituents at the germanium atom. In the thermolysis of hexamesitylcyclotrigermane ( 2 ), dimesitylgermylene ( 11 ) and tetramesityldigermene ( 8 ) are generated. While 11 can be trapped directly with 2,3-dimethyl-1,3-butadiene to give dimesitylger macyclopent-3-ene ( 9 ), 8 rearranges to mesityl(trimesityl)germylene ( 12 ), which leads to the formation of mesityl(trimesitylgermyl)germacyclopent-3-ene ( 10 ). Nevertheless, in the thermolysis of 2 with paraformaldehyde, thiobenzophenone, or phenylacetylene as trapping reagents the expected cyclo-adducts of tetramesityldigermene ( 8 ) are formed. Furthermore when hexamesitylcyclotrigermane ( 2 ) is reacted with acetylene in the presence of catalytic amounts of palladium complexes, a C-unsubstituted germole 21 is obtained in good y

Palladium(0)-catalyzed intra- and intermolecular cyclization reactions of allene episulfides

Abstract Palladium(0) catalyzed reaction of allene episulfide with DMAD yielded sulfur containing medium ring compounds. Allyl substituted allene episulfide afforded an intramolecular cyclization product, [2.1.1] thiahexane derivative via η 3 -thioallyl complex.

Decomposition of bis(silyldiazomethyl) polysilanes: formation of polysilabicyclo[1.m.n]alkane derivatives

Abstract The photolysis of bis(trimethylsilyldiazomethyl)disilane ( 4a ) in tert-butyl alcohol provided the tert-butyl alcohol adducts 5, 6, 7, 8 and 9 . The structures of these products revealed the stepwise formation of asymmetric silenes as intermediates. Gas-phase pyrolysis of 4a and subsequent reaction with methanol and 4-methyl-1,2,4-triazoline-3,5-dione yielded the compounds 13 and 14 , which are derived from the 1,4-disilabutadiene intermediate ( 16 ) rather than 1,2-disilacyclobutene ( 15 ). The photolysis and thermolysis of bis(dimethylphenylsilyl-diazomethyl)trisilane ( 4b ) afforded 21b, 22b, 23b and 24b . Formation of compound 21b is attributed to the head-to-tail [2 + 2]cycloaddition of 1,5-disila-1,4-pentadiene ( 26b ), while that of 23b, 22b and 24b is attributed to head-to-head [2 + 2]cycloaddition of 26 followed by reactions with tert-butyl alcohol and oxygen. Photolysis and pyrolysis of bis(trimethylsilyldiazomethyl)trisilane ( 4c ) and bis(dimethyl-phenylsilyldiazomethyl)tetrasilane ( 4d ) gave 29, 30 and 21d , which is consistent with an alternative mechanism, i.e. [2 + 2]silene-diazo cycloaddition.

The photochemical reaction of 1,2-digermacyclobutane with C60: possible example of a closed [6,5]-bridged fullerene derivative of germacyclopropane

Abstract The photolysis of 1,2-digermacyclobutane derivatives ( 1 ) with bulky bistrimethylsilylmethyl (disyl) groups in a toluene solution of C60 provided the germylene ( 2 ) and germacyclopropane ( 3 ) adducts of C60, respectively. The structures of the two products were characterized using 1 H- and 13 C-NMR spectra. The signals showed a dramatic change in line shape with temperature. The non-equivalence of the two disyl groups at high temperature, as well as the presence of quaternary aliphatic carbon, suggested that the germylene adduct ( 2 ) may be a closed [6,5] adduct: a possible first example of a closed [6,5]-bridged fullerene adduct. PM3 and ab initio calculations also support an energetically preferred closed [6,5] germacyclopropane adduct over an open [6,5] germa-annulene. The non-equivalence of the two disyl groups at low temperatures, as well as the presence of two methylene groups, indicated a germacyclopropane adduct ( 3 ), having a germacyclopentane structure that includes a closed [6,6] bond on the C60 surface. To take into account the regio-selective formation of the [6,5] adducts, a fragmentation mechanism of the digermacyclobutane on the C60 surface is proposed.

Singlet oxygenation of oxadisiliranes. Syntheses and crystal structure of 1,2,4,3,5-trioxadisilolanes

Singlet oxygenation of 2,2,3,3-tetraaryloxadisiliranes 1a-d gives the corresponding 1,2,4,3,5-trioxadisilolanes 2a-d, derivatives of a novel class of cyclic peroxides. The reaction mechanism is discussed in terms of possible peroxonium ion intermediate 6a as a nucleophilic oxidizing species.

Telluradigermiranes. A novel three-membered ring system containing tellurium

Reactions of hexamesitylcyclotrigermane (1a) and tetrakis(2,6-diethylphenyl)digermene (3b) with tellurium at 80 °C produce telluradigermiranes (2a) and (2b) respectively; the structure of (2b) has been confirmed by a single-crystal X-ray diffraction study, showing the existence of a Ge2Te ring.

Synthesis and Reaction of Novel Sulfur Containing Heterocyclic Systems

Abstract The strained alkylidene episulfides were synthesized by carbene and alkylidene carbene additions to thiocarbonyl compounds. Thermal, photochemical, and acid catalyzed reactions have been extensively investigated, and and the transition metal-promoted reaction results in the first isolation of thioallyl iron tricarbonyl complex. Germylene and zirconocene also reacted with thioketene to give metallic analogue of alkylidene episulfides, which are excellent synthetic source of a variety of cyclogermanes and stable enethiolizable thioaldehyde. Thermal sulfurization of some 1,2,3-butatriene derivatives and 1,2,3-selenadiazoles with elemental sulfur has been examined to give a variety of novel cyclic polysulfides having an unique structure. Reactive silicon and germanium species also reacted with elemental sulfur and selenium to afford cyclic metallachalcogenides.

Synthesis and reactivity of [3.1.1] and [2.1.1]silapropellanes

Abstract The dilithiated compound 3 reacted with 1,3-dichlorotrisilane to give [3.1.1]trisilapropellane 1 as a stable form. The reaction of 3 with 1,2-dichlorodisilane gave the ether-incorporated product 9 through [2.1.1]dislapropellane 13. Reductive coupling of the bissilylated tricyclo[4.1.0.02,7]heptane 23a also provided [3.1.1]disiloxapropellane 25 via the intermediate of [2.1.1]disilapropellane 24a. The compounds 1 and 25 show an unique reactivity in the presence of acid to give 7 and 27. The structures of 7 and 27 sharing common ring system have been determined by 2D-NMR and X-ray crystal analysis, respectively. Theoretical studies are also carried out by MNDO method.

SULFURIZATION OF 1,4,7,10-TETRAARYLCYCLODODECA-1,2,3,7,8,9-HEXAENES

Abstract Thermal reactions of 1,4,7,10-tetraarylcyclododeca-1,2,3,7,8,9-hexaenes1a and1b with elemental sulfur were examined, and found to give novel transannular bridged pentasulfides2a and2b, while cyclopentenethiones3a and3b were obtained by the sulfurization of1a and1b in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene.