3901-07-3Relevant articles and documents
Dieck,Heck
, p. 1133,1136 (1974)
Reversion of alignment direction in the thermally enhanced photoorientation of photo-cross-linkable polymer liquid crystal films
Kawatsuki, Nobuhiro,Goto, Kohei,Kawakami, Tetsuro,Yamamoto, Tohei
, p. 706 - 713 (2002)
Reversion of the in-plane reorientation direction of mesogenic groups has been observed for the first time in novel polymethacrylate liquid crystal (PLC) films substituted with a 4-methoxycinnamoyloxybiphenyl side group. The reversion was generated by irradiation with linearly polarized ultraviolet (LPUV) light and a subsequent annealing. Irradiation with LPUV light induces negative optical anisotropy of the films as a result of an axis-selective photoreaction of the side groups. The direction of the thermally enhanced reorientation is dependent on the degree of photoreaction and the distribution of photoproducts, while the induced orientational order in both directions, S, was larger than 0.5. The distribution of photoproducts in PLC films has been analyzed to elucidate their contribution to the thermally enhanced reorientation behavior. Initially upon photoreaction, thermal enhancement of the photoinduced negative optical anisotropy was observed. However, when the degree of photodimerization was 15% or greater, the direction of the thermally enhanced reorientation was found to be parallel to the polarization direction (E) of LPUV light. It is concluded that a small amount of photoproduct plays a role in the thermal amplification of the photoinduced negative optical anisotropy in a manner identical to that of PLC with azobenzene side groups. In contrast, photodimerized mesogenic groups generated reversion of the orientational direction and enhancement of positive optical anisotropy of the film through annealing.
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Curtin,D.Y.,Dayagi,S.
, p. 867 - 877 (1964)
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Recoverable cationic Pd-catalyzed Heck reaction under thermomorphic mode
Li, Chieh-Keng,Ghalwadkar, Ajay,Lu, Norman
, p. 3637 - 3642 (2011)
The reaction of allylpalladium chloride dimer and 4,4′-bis(R fCH2OCH2)-2,2′-bpy, 1a-c, in the presence of AgOTf resulted in the synthesis of cationic complex, [Pd(η3-allyl)(4,4′-bis-(RfCHs
Phosphine-Functionalized Chitosan Microparticles as Support Materials for Palladium Nanoparticles in Heck Reactions
Biajoli, André F. P.,Fajardo, André R.,Lemos, Thalia S. A.,de Souza, Jaqueline F.
, (2022/01/11)
Herein, we investigated the activation and stabilization of Pd nanoparticles using microparticles of chitosan-functionalized with phosphine moieties. The catalytic activity of the prepared material was assessed in a series of Heck reactions, which demonst
Pd-Catalyzed desulfitative arylation of olefins by: N -methoxysulfonamide
Ojha, Subhadra,Panda, Niranjan
supporting information, p. 1292 - 1298 (2022/02/19)
A novel Pd-catalyzed protocol for the desulfitative Heck-type reaction of N-methoxy aryl sulfonamides with alkenes was reported. The cross-coupling reaction was performed successfully with a variety of olefins to obtain aryl alkenes. Different substituents on the aromatic ring of N-methoxysulfonamides were also found to be compatible with the reaction conditions. Expectedly, the reaction proceeds through CuCl2-promoted generation of the nitrogen radical and subsequent desulfonylation under thermal conditions to afford the aryl radical for the Pd-catalyzed coupling reaction. N-Methoxysulfonamide was further exploited for the synthesis of symmetrical biaryls in the presence of CuCl2. This journal is
Solid-phase synthesis of coralmycin A/epi-coralmycin A and desmethoxycoralmycin A
Hawkins, Paige M. E.,Liu, Dennis Y.,Linington, Roger G.,Payne, Richard J.
supporting information, p. 6291 - 6300 (2021/07/28)
The total synthesis of the natural product coralmycin A/epi-coralmycin A, as well as a desmethoxy analogue is described. Synthesis was achievedviaa divergent, bidirectional solid-phase strategy, including a key on-resinO-acylation,OtoNacyl shift, andO-alkylation protocol to incorporate the unusual 4-amino-2-hydroxy-3-isopropoxybenzoic acid motifs. The synthetic natural product was generated as a 1?:?1 mixture of epimers at the central β-methoxyasparagine residue and exhibited potent antibacterial activity against a panel of ten Gram-negative and seven Gram-positive organisms. The desmethoxy analogue possessed significantly more potent antimicrobial activity against this panel with minimal inhibitory concentrations (MICs) as low as 50 nM.
