22808-03-3

π-Conjugated polymers, PTOTBT, PTEHTBT, and PTt-BTBT, composed of benzothiadiazole as an electron accepting unit and terthiophene as an electron donating unit in the backbone were prepared. PTOTBT, PTEHTBT, and PTt-BTBT contained side chain groups of n-octyl, 2-ethylhexyl, and t-butyl groups, respectively. Solubility, optical and thermal properties of the polymers showed strong dependences on their side chain groups. PTEHTBT having 2-ethylhexyl groups in the side chain exhibited absorption maximum (Imax) at longer wavelength (565 nm) than PTOTBT (534 nm) and PTt-BTBT (495 nm). PTOTBT showed higher thermal stability than the others. The prepared polymers were employed to polymer solar cells (PSCs) with a configuration of ITO/PEDOT-PSS/polymer: PC61BH/LiF/Al. Power conversion efficiency of the PSC-based on PTEHTBT was 1.32%.

A successful synthesis of the hitherto unknown 3,4-di-t-butylthiophen and the results of its crystal structure determination are reported.

The synthesis of a new octa-tert-butylphthalocyanine is described. First, the 4,5-di-tert-butylphthalonitrile building block was synthesized in a six-step approach, in which the last step is a three reaction domino sequence. Then, this phthalonitrile was cyclotetramerized to furnish a new phthalocyanine dye, which presented no aggregation in solution and good photophysical properties. The synthesis of a new octa-tert-butylphthalocyanine is described. First, the 4,5-di-tert-butylphthalonitrile building block was synthesized in a six-step approach, in which the last step is a three reaction domino sequence. Then, this phthalonitrile was cyclotetramerized to furnish a new phthalocyanine dye, which presented no aggregation in solution and good photophysical properties. Copyright

Hetero Diels-Alder reactions of 3,4-di-tert-butylthiophene 1-oxide (1) with thioaldehydes and thioketones take place exclusively, except the reaction with thiobenzophenone, at the syn-π-face of 1 with respect to the S=O bond. The π-face selectivity was ex

Treatment of the tetrahydrothiophene-3,4-diol 5 with 1,1′-thiobis- (1H-benzimidazole) (6) furnished two diastereoisomers of the novel cyclic thionosulfite 4 with different configurations at the pseudo-tetrahedral center of the thiosulfinyl (S=S) group. The configuration of the S=S group of the major diastereoisomer (isolated in 45% yield) was established to be syn to the thiolane ring, as determined by X-ray crystallographic analysis, while that of the minor diastereoisomer (isolated in 10% yield) was anti. 1H-NMR Spectroscopic analysis clarified that the shielding and deshielding zones of the S=S group are similar to those of the well-documented S=O group. Characteristic absorptions of the S=S group in the IR, Roman, and UV/VIS spectra were assigned on the basis of calculations at the B3LYP/6-31G* level. The reactivity of the S=S group toward thermolysis, hydrolysis, and oxidation was examined. The S=S group is more resistant toward oxidation than the divalent sulfide S-atom, but is oxidatively converted to the S=O group.

3,4-Di-t-butylthiophene (1) was surprisingly easily synthesized from readily accessible bis(2-t-butyl-2-oxoethyl) sulfide (2).Reactions of 1 with a variety of electrophiles were examined.

The reaction of 3,4-di-tert-butylthio-phene 1-oxide (8) with tetrachlorocyclopropene provided 6,7-di-tert-butyl-2,3,4,4-tetrachloro-8-thia- bicylo[3.2.1]-octa-2,6-diene 8-oxide (10), which was oxidized to the corresponding 8,8-dioxide 16 by m-chloroperbenzoic acid. The thermolysis of 16 in refluxing chlorobenzene, xylene, or octane gave 5-tert-butyl-1,2-dichloro-3- [(1,1-dichloro-2,2-dimethyl)propyl]benzene (18) with extrusion of SO2 and 2-tert-butyl-4,5,6-trichloro-9,9-dimethylbicyclo[5.2.0]nona-1,3,5-triene (19) with extrusion of SO2 and HCl in 73-78% combined yields. On the other hand, the thermolysis of 16 in the presence of triethylamine gave 19 as the sole product in 98% yield. A mechanism that involves the initial formation of 4,5-di-tert-butyl-1,2,7,7-tetrachlorocycloheptatriene (17) is proposed to explain the observed products.

It was found that tetracyanoethylene oxide not only oxidizes sulfides to sulfoxides but also reduces sulfoxides to sulfides with generation of two molecules of carbonyl cyanide. The reaction thus also functions as a new method for generation of carbonyl cyanide.

5,6-Di-tert-buty(-2,3,7-trithiabicyclo[2.2.1]hept-5-ene 7-endo-oxide (4) was prepared by addition of S2Cl2 to 3,4-di-tert- butylthiophene 1-oxide (3) in high yield. The oxidation of 4 with dimethyldioxirane gave a 7:1 isomeric mixture of 5,6-di-tert-butyl-2,3,7- trithiabicyclo[2.2.1]hept-5-ene 2-endo-7-endo-dioxide (5a) and 2-exo-7-endo-dioxide (5b) quantitatively. The thermally labile 5 was shown to undergo a retro-Diels-Alder reaction that produces S2O and 3 in a reversible way. The resulting S2O was trapped by Diels-Alder reactions with dienes to give 3,6-dihydro-1,2-dithiin 1 -oxides in good yields. In the absence of the dienes, S2O disproportionates to SO2 and S3, and the resulting S3 underwent a 1,3-dipolar cycloaddition with 3 on its syn-π-face with respect to the S=O bond to give a trithiolane derivative, whereas in the presence of excess norbornene, it produced the 1,3-dipolar cycloadduct with norbornene in good yield. Thus, the retro-Diels-Alder reaction of 5 functions as an S2O and S3 source. DFT calculations at the B3LYP/6-311+G(3df,2p) level were carried out in order to explain why S2O disproportionates to SO2 and S3 and why S2O acts as a dienophile and not 1,3-dipole, whereas O3 and S3 serve as 1,3-dipoles.

The pseudotetrahedral geometry of the thiosulfinyl group (>SS) in the thionosulfite which was prepared by treatment of cis-3,4-di-tert-butylthiolane-3,4-diol with 1,1'-thiobisbenzimidazole is stable enough to allow the isolation of two diastereomers. X-ray crystallographic analysis revealed that the configuration of the >S S group of the major diastereomer (45% isolated yield) is syn to the thiolane ring, while that of the minor diastereomer (10% isolated yield) is anti to the thiolane ring. 1H NMR spectrum analysis clarified that the shielding and deshielding zones of the >SS group are similar to those >SS group; Chemical properties of the > 5 S group toward thermolysis, hydrolysis, and oxidation were clarified. The absorptions or bands in the UV/ vis IR and Raman spectra, which originate from the > SSgroup, were assigned on the basis of the B3LYP/ 6-31G* level calculations. Copyright

Treatment of 3,4-di-t-butylthiophene 1-oxide with (CF3CO)2O or (CF3SO2)2O, followed by reaction with RSO2NH2, ROC(=O)NH2, or RCONH2 furnished a series of 1-

Highly congested thiophenes, 3,4-di-tert-butyl-, 3,4-di(1-adamantyl)-, 3,4-dineopentyl-, and 3-(1-adamantyl)-4-tert-butylthiophenes (4a-d), were prepared in satisfactory overall yields by intramolecular reductive coupling of 3-thiapentane-1,5-diones (1a-d) followed by acid-catalyzed dehydration of the resulting thiolane-3,4-diols (2a-d). Experimental procedures of this thiophene synthesis are fully described. Oxidation of the thiophenes 4a-d with m-CPBA gave the corresponding thiophene 1,1-dioxides 13a-d in good yields. The Diels-Alder reactions of 13a-d with phenyl vinyl sulfone gave o-di-tert-butyl-, o-di(1-adamantyl)-, o-dineopentyl-, and o-(1-adamantyl)-tert-butylbenzenes (17a-d) directly in high yields with loss of benzenesulfinic acid and sulfur dioxide. The dioxides 13a-d also underwent Diels-Alder reactions with alkynic dienophiles to give the corresponding benzene derivatives carrying two bulky substituents on adjacent positions. Pyridazines 25b,c, carrying bulky substituents on the 4- and 5-positions, were also synthesized through Diels-Alder reaction of 13b,c with PTAD. Dimethylation of the 2- and 5-positions of 13a-d was attained by treatment with strong bases followed by reactions with methyl iodide. The resulting tetrasubstituted thiophene 1,1-dioxides 14a-d reacted with DMAD to give highly congested hexasubstituted benzene derivatives 15a-d in good yields. Finally, structural features of the congested molecules are discussed on the basis of NMR analyses. Typically, the barriers to rotation (ΔH?) about the benzene to the bulky substituents of 15a,c,d were determined to be 8.59, 15.3, and 7.40 kcal/mol, respectively, by NMR total line-shape analysis.

The oxidation of 3,4-di-tert-butylthiophene 1,1-dioxide (4) by a variety of reagents under various conditions was investigated in detail.Oxidation of 4 with peracids (MCPBA, trifluoroperacetic acid) affords the thiete 1,1-dioxide 6 and the sulfone 7, both in moderate yield.The formation of these compounds can be explained as being the result of an acid-catalyzed rearrangement of the initial product, epoxy sulfone 5 via the carbocation 8.Under basic conditions the rearrangement is suppressed and thus 5 can be isolated in good yield.Treatment of 5 with BF3*Et2O affords 6 and the sultine 10.Oxidation of 4 with alkaline H2O2 involves a smooth Michael addition of HOO- to give the hydroperoxide 17 in high yield.This represents the first example of the formation of an isolable β-hydroperoxy sulfone, a species which has been hypothesized to be an intermediate in the formation of epoxy sulfones by the oxidation of α,β-unsaturated sulfones with alkaline H2O2.Thermal decomposition of 17 affords the ketone 19 quantitatively.Reduction of 17 with NaBH4 gives the alcohol 20.On treatment with base, both 17 and 20 undergo ring opening to yield the alkene 18 in good yield.

3,4-Di-t-butylfuran (1), pyrrole (2), and selenophene (4) were first synthesized using 3,4-di-t-butylthiophene (3) as the starting material and these overcrowded five-membered hetarenes including 3 were characterized by NMR and MMP2 calculations.