21454-60-4Relevant articles and documents
Cascade reaction for the synthesis of polycyclic aromatic hydrocarbons via transient directing group strategy
Wang, Ziqi,Dong, Wendan,Sun, Bing,Yu, Qinqin,Zhang, Fang-Lin
supporting information, p. 4031 - 4041 (2019/07/03)
A Pd(II)-catalyzed cascade synthesis of diverse polycyclic aromatic hydrocarbons via transient directing group strategy has been developed, involving the consecutive arylation, cyclization and aromatization. The efficiency and practicality were demonstrated by wide substrate range, concise synthetic pathway and mild reaction conditions. The subsequent transformations of the benz[a]anthracene core accessed natural bioactive PAH molecules.
Direct synthesis of anthracenes from o-tolualdehydes and aryl iodides through Pd(II)-Catalyzed sp3 C–H arylation and electrophilic aromatic cyclization
Park, Hyojin,Yoo, Kwangho,Jung, Byunghyuck,Kim, Min
, p. 2048 - 2055 (2018/03/13)
The first direct synthesis of substituted anthracenes from o-tolualdehydes and aryl iodides via a Pd(II)-catalyzed C–H arylation using an alcohol-bearing transient directing group and subsequent AgOTf-assisted electrophilic aromatic cyclization is described. New transient directing groups consisting of amino acids and amino alcohols enhanced the reactivity, and the C–H arylation was complete in 12 h at 90 °C. By simply changing the silver salt to silver triflate, the one-pot synthesis of anthracene derivatives was carried out using the present reaction conditions.
Facile Synthesis of Polycyclic Aromatic Hydrocarbons: Br?nsted Acid Catalyzed Dehydrative Cycloaromatization of Carbonyl Compounds in 1,1,1,3,3,3-Hexafluoropropan-2-ol
Fujita, Takeshi,Takahashi, Ikko,Hayashi, Masaki,Wang, Jingchen,Fuchibe, Kohei,Ichikawa, Junji
, p. 262 - 265 (2017/01/24)
The cycloaromatization of aromatic aldehydes and ketones was readily achieved by using a Br?nsted acid catalyst in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP). In the presence of a catalytic amount of trifluoromethanesulfonic acid, biaryl-2-ylacetaldehydes and 2-benzylbenzaldehydes underwent sequential intramolecular cationic cyclization and dehydration to afford phenacenes and acenes, respectively. Furthermore, biaryl-2-ylacetaldehydes bearing a cyclopentene moiety at the α-position underwent unprecedented cycloaromatization including ring expansion to afford triphenylenes. HFIP effectively promoted the cyclizations by suppressing side reactions presumably as a result of stabilization of the cationic intermediates.
Stable simple enols. Resolution of chiral 1-[9′-(2′-fluoroanthryl)]-2,2-dimesitylethenol. A different racemization mechanism for the enol and its acetate
Rochlin, Elimelech,Rappoport, Zvi
, p. 216 - 226 (2007/10/03)
Chiral 1-[9′-(2′-methoxyanthryl)]-2,2-dimesitylethenol (2), 1-[9′-(2′-fluoroanthryl)]-2,2-dimesitylethenol (3), and 1-[9′-(2′-fluoroanthryl)]-2,2-dimesitylvinyl acetate (4) were synthesized and their DNMR behavior in C6D5NO2 was studied. 3 and 4 were resolved on an amylose tris(3,5-dimethylphenylcarbamate) HPLC column to their enantiomers. Acetate 4 racemizes slowly in solution with ΔGe?, ΔHe?, and ΔSe? values of 26.2, 27.6 kcal mol-1, and 4.3 eu, respectively, as expected for a rotational ββ′-2-ring flip process in a vinyl propeller and the racemization is unaffected by added TFA, Et3N, and EtOD. Although 3 racemizes almost 350 times faster, the racemization is catalyzed by TFA and shows bell-shape catalysis by Et3N and a KIE in a partially deuteriated solvent. From this and the DNMR data, it is concluded that 3 does not racemize via a rotational ββ′-2-ring flip. Five nonflip routes are discussed for the racemization of 3, and it is concluded that only the one initiated by protonation at C1 does not contradict the experimental data. By analogy with the E/Z isomerization of the structurally related 2-(m-methoxymesityl)-1,2-dimesitylethenol 17, it is suggested that in the absence of added catalyst one or more enol molecule(s) catalyze the enantiomerization of another one. Only partial resolution was achieved for 2 and from the similarity of its behavior with that of 3, it is suggested that it racemizes by the same mechanism.
