- Photomechanical response of sulfonylhydrazone molecular crystals
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Sulfonylhydrazones are a novel hydrazone-based organic molecular photoswitch. The four derivatives with unsubstituted ando-,m- andp-nitro substituted sulfonylhydrazone (SH-1,SH-2,SH-3, andSH-4, respectively) derived fromp-toluenesulfonyl hydrazide and corresponding benzaldehydes were examined with respect to their solution state photoswitching and photomechanical response in the crystalline state. All the compounds displayed UV-inducedE→Zisomerization in the solution state, whereas the back conversion was slow. Single crystals ofSH-3displayed rapid and large photomechanical bending, whereasSH-1andSH-4crystals underwent slow bending to a comparatively lesser extent. On the contrary,SH-2crystals did not show any photomechanical effects. The photomechanical deflection of the crystal tip ofSH-1increased linearly; forSH-3, the deflection increased in a sub-linear manner for few seconds, after which it started to revert towards the light source. ForSH-4crystals, the photo-induced tip deflection initially increased in a sub-linear fashion, after which no motion was observed even after continuous exposure to UV light irradiation. The photomechanical behavior of the crystals was also inspected with the aid of velocity-time and acceleration-time plots that unravelled the instantaneous photomechanical motion at various time intervals.
- Allu, Suryanarayana,Gunnam, Anilkumar,Gupta, Poonam,Hazarika, Pragyan J.,Nangia, Ashwini K.,Nath, Naba K.
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p. 4910 - 4916
(2021/07/25)
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- Highly stereoselective synthesis of 1-cyanocyclopropane-carboxamides from 3-substituted-2-cyanoacrylamides with N-tosylhydrazones under metal-free conditions
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A metal-free cyclopropanation of electron-deficient olefins 3-substituted-2-cyanoacrylamides with N-tosylhydrazones has been successfully developed. This strategy provide a simple route to the synthesis of very valuable 1-cyanocyclopropanecarboxamides wit
- Nie, Xufeng,Wang, Yachuan,Yang, Lijun,Yang, Zaijun,Kang, Tairan
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supporting information
p. 3003 - 3007
(2017/07/17)
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- Iron(III) phthalocyanine-chloride-catalyzed synthesis of sulfones from sulfonylhydrazones
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In this study, sulfones are synthesized from sulfonylhydrazones catalyzed by iron(III) phthalocyanine chloride. This reaction offers broad substrate scope, occurs under mild conditions, utilized readily available reactants, and forms products in good-to-h
- Zhao, Jun-Long,Guo, Shi-Huan,Qiu, Jun,Gou, Xiao-Feng,Hua, Cheng-Wen,Chen, Bang
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supporting information
p. 2375 - 2378
(2016/05/19)
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- Efficient synthesis of 1,5-disubstituted carbohydrazones using K 2CO3 as a carbonyl donor
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A novel reaction that generates 1,5-disubstituted carbohydrazones via the carbonylation of tosylhydrazones has been developed. For the first time, the inexpensive, readily available, environmentally friendly, and nongaseous potassium carbonate is used as
- Wen, Jun,Yang, Chu-Ting,Jiang, Tao,Hu, Sheng,Yang, Tong-Zai,Wang, Xiao-Lin
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supporting information
p. 2398 - 2401
(2014/05/20)
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- A complementary approach to 3,5-substituted pyrazoles with tosylhydrazones and terminal alkynes mediated by TfOH
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A complementary method for the preparation of 3,5-substituted pyrazoles in moderate to high yields has been explored via TfOH-induced addition of tosylhydrazones to the terminal alkynes. This acid-induced addition procedure might be an operationally safe alternative compared to typical 1,3-dipolar cycloaddition as there is no involvement of diazo compounds.
- Liu, Ping,Xu, Qian-Qian,Dong, Chao,Lei, Xinsheng,Lin, Guo-Qiang
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supporting information
p. 2087 - 2092
(2012/11/07)
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- Synthesis of substituted 1 H-indazoles from arynes and hydrazones
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The 1H-indazole skeleton can be constructed by a [3 + 2] annulation approach from arynes and hydrazones. Under different reaction conditions, both N-tosylhydrazones and N-aryl/alkylhydrazones can be used to afford a variety of indazoles. The former reaction affords 3-substituted indazoles either via in situ generated diazo compounds or through an annulation/elimination process. The latter reaction leads to 1,3-disubstituted indazoles likely through an annulation/oxidation process. The reactions operate under mild conditions and can accommodate aryl, vinyl, and less satisfactorily, alkyl groups.
- Li, Pan,Wu, Chunrui,Zhao, Jingjing,Rogness, Donald C.,Shi, Feng
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experimental part
p. 3149 - 3158
(2012/07/14)
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- C(sp)-C(sp3) bond formation through cu-catalyzed cross-coupling of N -tosylhydrazones and trialkylsilylethynes
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Copper-catalyzed cross-coupling of N-tosylhydrazones with trialkylsilylethynes leads to the formation of C(sp)-C(sp3) bonds. Cu carbene migratory insertion is proposed to play the key role in this transformation.
- Ye, Fei,Ma, Xiaoshen,Xiao, Qing,Li, Huan,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 5742 - 5745
(2012/05/07)
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- Synthesis of 3-substituted indazoles from arynes and N-tosylhydrazones
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Readily available, stable, and inexpensive N-tosylhydrazones react with arynes under mild reaction conditions to afford 3-substituted indazoles in moderate to good yields. The reaction appears to involve a dipolar cycloaddition of in situ generated diazo
- Li, Pan,Zhao, Jingjing,Wu, Chunrui,Larock, Richard C.,Shi, Feng
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supporting information; experimental part
p. 3340 - 3343
(2011/09/12)
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- A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities
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A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.
- Aggarwal, Varinder K.,Alonso, Emma,Bae, Imhyuck,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Patel, Mamta,Porcelloni, Marina,Richardson, Jeffery,Stenson, Rachel A.,Studley, John R.,Vasse, Jean-Luc,Winn, Caroline L.
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p. 10926 - 10940
(2007/10/03)
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- Alkylation of Aldehyde (Arenesulfonyl)hydrazones with Trialkylboranes
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(Arenesulfonyl)hydrazone derivatives of aryl aldehydes are readily alkylated by trialkylboranes in the presence of base to generate new organoboranes that may be converted to the corresponding substituted alkanes or alcohols depending upon the reaction conditions chosen. Both tosyl- and trisylhydrazone derivatives can be utilized in the reaction, which tolerates a variety of functional groups, making it a versatile alternative to both the Grignard and Suzuki-coupling reactions.
- Kabalka, George W.,Maddox, John T.,Bogas, Ekaterini,Kelley, Shane W.
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p. 3688 - 3695
(2007/10/03)
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