Yasuhiro Nakadaira

Chemistry of organosilicon compounds

Abstract Two new 1,2-disilacyclobutenes have been prepared by the reaction of tetramethyldisilene with acetylenes. Several reactions of these new 1,2-disilacyclobutenes including oxidation, silylene insertion, iron carbonyl insertion, and addition to acetylenes and dienes are reported.

Structures and properties of the sugars obtained from the chromomycins

Abstract The water soluble fraction of the acid hydrolysate of chromomycin A 3 when chromatographed on cellulose powder yields four new sugars chromose A, chromose B, chromose C and chromose D. The structures of these sugars have been elucidated. Interstingly, all four are 2,6-dideoxy sugars, and furthermore, chromose B belongs to the L-series while the other three are D-sugars. the hydrolysis of chromomycin A 2 affords a fifth sugar, which has been identified as 4-O-isobutyryldeacetylchromose B.

Chemistry of organosilicon compounds: CCXVI. Sterically crowded silanes

Abstract Some highly crowded silanes, such as tri-t-butylphenyl,tri-iso-propylphenyl, tris(trimethylsilyl)methyl,t-butyl and mesityl substituted silanes, have been prepared and the order of steric bulkiness of these substituents is estimated.

Novel alkylation of aromatic nitriles via photo-induced electron transfer of group 14 metal-carbon σ donors

Abstract Photo-induced electron transfer reactions of tetraalkylsilanes, -germanes, and -stannanes with aromatic nitriles afforded alkylated products. The mechanism was investigated by use of a radical clock.

Chemistry of organosilicon compounds: CLXXXVIII. Reaction of organodisilanes with dienes catalyzed by transition metal complexes. Preparation of 1,8-bis(trimethylsilyl)octa-2,6-diene and its use in the synthesis of dl-muscone☆☆☆

Abstract Organodisilanes, Me 3- n X n SiSiX n Me 3- n (X = Cl and MeO, n = 0, 1, 2) undergo efficient 1:2 addition reactions with butadiene and isoprene in the presence of a catalytic amount of a suitable palladium complex. One of the products, the title compound, was used as a starting material for a short synthesis of dl -muscone.

Chemistry of organosilicon compounds 118. Novel ring contraction reaction of (η4-1,2-disilacyclohexadiene)iron tricarbonyls

Abstract 1,1,2,2-Dimethyl-3,6-diphenyl-1,2-disilacyclohexadiene reacts with iron pentacarbonyl or diiron nonacarbonyl to give the corresponding (diene)iron tricarbonyl complex which undergoes novel ring contraction reaction to (η 4 -1,1-dimethyl-2,5-diphenyl-1-silacyclopentadiene)iron tricarbonyl on thermolysis at 160°C. Similar results were observed with 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disilacyclohexadiene.

Chemistry of organosilicon compounds XCVI. The SiSi/SiSi Metathesis reaction catalyzed by palladium complexes☆

Abstract 1,1,2,2-Tetramethyl-1,2-disilacyclopentane undergoes the SiSi/SiSi metathesis reaction with vinyl- or ethynyl-substituted disilanes in the presence of a palladium complex.

Tetrakis(trimethylsilyl)ethylene and related compounds, crowded olefins☆

Abstract Tetrakis(trimethylsilyl)ethylene (1), tris(trimethylsilyl) (dimethylsilyl)ethylene and 1,2-bis(trimethylsilyl)-1,2-bis(dimethylsilyl)ethylene have been prepared and spectral properties are described. ESR spectra of anion and cation radicals of 1 are also recorded, indicating a nonplanar twisted structure for 1. These crowded olefins show interesting reversible thermochromism.

Synthesis and oxidation of 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disila-3,4-cyclohexadiene

Abstract The synthesis of 1,1,2,2-tetramethyl-3,4,5,6-tetraphenyl-1,2-disila-3,4-cyclohexadiene, (I), from 1,4-dilithiotetrapheynylbutadiene and 1,2-dichlorotetramethyldisilane is described. (I) is reluctant to react with singlet oxygen, in contrast to its carbon analogue, but the SiSi bond of(I) is readily oxidized to give 2,2,7,7-tetramethyl- 3,4,5,6-tetrapheynyl-1-oxo-2,7-disila-3,5-cycloheptadiene. The mechanism of the formation of this siloxane is discussed, and a peroxy radical shown to act as an important intermediate in the oxidation.

The reactions of chromomycinone and derivatives

Abstract The various reactions of chromomycinone, the chromophore of the cancerostatic chromomycins, are described. The structures of several chromomycinone derivatives are also discussed.