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91.
Matthew C. Davis 《合成通讯》2013,43(20):3519-3528
A rapid method to prepare 1,3,5‐triaminobenzene and its derivatives is the tris‐Curtius rearrangment of 1,3,5‐benzenetricarboxylic acid. The hazards associated with the acyl azide route are minimized by using 1,2‐dichloroethane as solvent. A second method that avoids acyl azide preparation uses diphenylphosphoryl azide to yield the tricarbamate in one step. 相似文献
92.
An atom-economic route to densely functionalized thiophenes has been developed via base-catalyzed rearrangement of 5-propargyl-2H-thiopyran-4(3H)-ones involving tandem retro-thio Michael addition, propargyl isomerization, and intramolecular thio-addition to allenes. 相似文献
93.
AbstractA simple and facile method for the denitrosation of cyclic N-nitrosamines using HN3 (concentrated H2SO4 + NaN3) is reported. In this method, limited usage of this reagent does not affect the carbonyl group. 相似文献
94.
Liladhar Waykole Mahavir Prashad Stephen Palermo Oljan Repic Thomas J. Blacklock 《合成通讯》2013,43(12):2159-2163
A practical synthesis of 2-(bromomethyl)naphthalene (1), by selective benzylic bromination of 2-methylnaphthalene (2), with bromine in heptane in the presence of lanthanum acetate hydrate is described. 相似文献
95.
96.
4‐Mercaptothiocoumarin was alkylated with different propargylic and allylic halides under phase‐transfer‐catalyzed conditions in the presence of tetrabutylammonium bromide (TBAB) or benzyl triethylammonium chloride (BTEAC) catalyst in dichloromethane–aqueous NaOH solution (1%) at room temperature. These 4‐thiopropynyl and thioallyl thiocoumarins were then refluxed in chlorobenzene and quinoline to give thiopyrano[3,2‐c][1]benzothiopyran‐5(2H)‐one and thiopyrano[3,2‐c][1]benzothiopyran‐4‐one respectively. 相似文献
97.
Stereoselective route to tricyclo[5.3.1.01,5]undecane and bicyclo[4.2.0]octane ring systems present in the molecular structure of tricycloillicinone, cedrenoids and endiandric acid, elysiapyrones, respectively, is described. A tandem oxidative dearomatization of o-hydroxymethylphenol, π4s+π2s cycloaddition, reactivity modulation in excited state and ring-closing metathesis are the key features of our approach. 相似文献
98.
A mild and selective transition metal free protocol for the conversion of propargylic alcohols to cyclic and acyclic α,β-unsaturated enones via the Rupe rearrangement is reported. The method utilizes the Brønsted acidic ionic liquid [BMIM-SO3H][OTf] as catalyst and [BMIM][PF6] as solvent and offers the potential for recycling and reuse of the IL solvent. The feasibility to synthesize bicyclic fused cyclopentenone derivatives via a Rupe → Aldol → Nazarov sequence utilizing this protocol has also been demonstrated. 相似文献
99.
A new liquid crystalline material containing diester linking group ethyl-[4-(4′-decyloxy)benzoyloxy]-benzoate (4-EDBB) was synthesized. The phase transition temperatures were noted by differential scanning calorimetry (DSC), the texture pattern were observed by polarizing optical microscopy (POM) and temperature dependent Raman study was employed to observe the transitions as well as to understand the molecular rearrangement during phase transition. The transitions were observed with all the three techniques but the Raman signature of crystal → smectic A transition is many fold and more precise and accurate. The correlation between intermolecular interaction and phase behaviour has been discussed using temperature dependence Raman data of CH in-plane bending and CO stretching vibrations. With the help of DFT method the possible dimers of 4-EDBB were optimized and the rotational isomers were also investigated. There exists weak hydrogen bonds at room temperature, which breaks as the temperature is increased causing the CH in-plane bending to shift lower and CO stretching vibrations to shift higher. The discussion of the temperature dependent Raman data reveals that at crystal → smectic A transition as a result of intra-molecular rotation the molecules transform from trans- to cis- conformer. 相似文献
100.
The problem of sorting by a genome rearrangement event asks for the minimum number of that event required to sort the elements of a given permutation. In this paper, we study a variant of the rearrangement event called prefix and suffix transreversal. A transreversal is an operation which reverses the first block before exchanging two adjacent blocks in a permutation. A prefix (suffix) transreversal always reverses and moves a prefix (suffix) of the permutation to another location. Interestingly, we will apply transreversal not on permutations but on strings over an alphabet of fixed size. We determine the minimum number of prefix and suffix transreversals required to sort the binary and ternary strings, with polynomial time algorithms for these sorting problems. 相似文献