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Journal of Organic Chemistry

Meng-Yang Chang, Yu-Ting Hsiao
H2SO4 mediated one-pot stereocontrolled (4+2) annulation of 4-alkenols and oxygenated naphthalenes provided tetanthrenes in CH2Cl2 at 25 degrees C for 10 h. The use of various Brønsted acids or Lewis acids was investigated for a facile and efficient transformation. A plausible mechanism has been proposed.
September 21, 2017: Journal of Organic Chemistry
Zhuo-Ya Mao, Chang-Mei Si, Yi-Wen Liu, Han-Qing Dong, Bang-Guo Wei, Guo-Qiang Lin
In this report, originally proposed apratoxin E (30S-7), revised apratoxin E (30R-7), and (30S)/(30R)-oxoapratoxin E (30S)-38/(30R)-38 were efficiently prepared by two synthetic methods. The chiral lactone 10, recycled from the degradation of saponin glycosides, was utilized to prepare the key non-peptide fragment 9. Our alternative convergent assembly strategy was applied to the divergent synthesis of revised apratoxin E and its three analogs. Moreover, ring-closing metathesis (RCM) was first time found to be an efficient strategy for the macrocyclization of apratoxins...
September 21, 2017: Journal of Organic Chemistry
Soumen Biswas, Debashis Majee, Soumitra Guin, Sampak Samanta
An efficient, solvent-free and eco-friendly domino reaction of 5/6-membered cyclic sulfamidate imines with a variety of β,γ-unsaturated α-ketocarbonyls in a neat condition under MW irradiation promoted by DABCO as a solid organobase has been developed for the rapid construction of a novel class of densely functionalized picolinates. This interesting metal-solvent-free tactic allows allows a wide range of useful functionalities on the aryl rings and delivers good to excellent yields of the aforesaid aza-heterocycles within short span of times (20-40 min)...
September 21, 2017: Journal of Organic Chemistry
Yasunari Monguchi, Masahiro Mizuno, Tomohiro Ichikawa, Yuki Fujita, Eri Murakami, Tomohiro Hattori, Tomohiro Maegawa, Yoshinari Sawama, Hironao Sajiki
In the presence of palladium on carbon (Pd/C) as a catalyst, hydrogenation of aliphatic nitriles in cyclohexane efficiently proceeded at 25-60 °C under ordinary hydrogen gas pressure to afford the corresponding tertiary amines. On the other hand, the use of rhodium on carbon (Rh/C) led to the highly selective generation of secondary amines. Hy-drogenation of aromatic nitriles and cyclohexanecarbonitrile selectively produced secondary amines in the presence of either Pd/C or Rh/C.
September 21, 2017: Journal of Organic Chemistry
Yu-Feng Lin, Chi Fong, Wan-Ling Peng, Kuei-Chien Tang, Yi-En Liang, Wen-Tai Li
An efficient strategy for synthesizing 3-(2-olefinbenzyl)-4H-chromen-4-one in two steps was developed. The first step is a cyclobenzylation reaction between (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one and benzyl bromide to produce homoisoflavonoid. The second step involves intermolecular Pd-catalyzed π-chelating-assisted C-H bond olefination. Using the C-2/C-3 double bond of chromone, palladium-catalyzed aryl C-H bond activation can be functionalized to generate ortho-olefination derivatives in moderate to high yields...
September 21, 2017: Journal of Organic Chemistry
Alba Molina, Ana Pascual-Escudero, Javier Adrio, Juan C Carretero
A three step reaction sequence has been developed to prepare a variety of enantioenriched pyrroloisoquinoline derivatives. The process involves a catalytic asymmetric azomethine ylide 1,3-dipolar cycloaddition followed by an intramolecular AuI catalyzed alkyne hydroamination and enamine reduction.
September 21, 2017: Journal of Organic Chemistry
Yang-Zi Liu, Shao-Jing Shang, Wu-Lin Yang, Xiaoyan Luo, Wei-Ping Deng
A highly efficient asymmetric 1,3-dipolar cycloaddition of azomethine ylides to β,β-disubstituted β-fluoro-acrylates catalyzed by a chiral N,O-ligand/Cu(CH3CN)4BF4 system is reported, affording chiral densely-substituted pyrrolidines with four contiguous stereocenters, including one fluorinated quaternary stereocenter at the 3-position, in good to excellent yields (up to 99%), with excellent levels of diastereo- and enantioselectivities (dr >20:1; ee up to 99%).
September 21, 2017: Journal of Organic Chemistry
Minh H Nguyen, Kevin T O'Brien, Amos B Smith Iii
The initial rational design, synthesis and validation of polymer-supported siloxane transfer agents have been achieved that permit the direct use of organolithium reagents in the palladium-catalyzed cross-coupling reactions. Through rational design, two generations of polymer support were developed that significantly simplify product purification and the transfer agent recycling.
September 20, 2017: Journal of Organic Chemistry
Shan Jiang, Hong-Mei Guo, Sheng Yao, De-Qing Shi, Wen-Jing Xiao
An efficient 1,3-dipolar cycloaddition of 3-ylideneoxindoles with in situ-generated α-diazoketones to potentially biological active spiro[pyrazolin-3,3'-oxindoles] 4 with excellent regioselectivity and diastereoselectivity and synthetically useful building block 3-arylcarbonylmethyl substituted ylideneoxindoles 5 in different conditions has been developed. This method has advantages of mild conditions, simple work-up, wide substrate scopes as well as without using any transition metal catalyst.
September 20, 2017: Journal of Organic Chemistry
Xiaobo Pang, Mingzhong Wu, Jixiang Ni, Fuming Zhang, Jingfeng Lan, Baohua Chen, Rulong Yan
One-pot Cu-catalyzed tandem aerobic oxidative cyclization for the synthesis of quinolines from 2-vinylanilines/2-aryl anilines and 2-methylquinolines via C(sp3)-H/C(sp2)-H bonds functionalization has been developed. Dioxygen as an ideal oxidant has been employed for this transformation. The substrates bearing various functional groups are performed well in this process and generate the desired products in moderate to good yields.
September 20, 2017: Journal of Organic Chemistry
Basil M Ahmed, Nicholas A Rudell, Ixtlazihuatl Soto, Gellert Mezei
The reaction of amines with aldehydes and ketones has been exploited for over 150 years to produce Schiff bases, one of the most popular classes of compounds in both organic and coordination chemistry. In certain cases, however, compounds other than Schiff bases have been reported to result from such reactions. After conducting a representative reaction under various different conditions and identifying several reaction intermediates by NMR spectroscopy, mass spectrometry and X-ray crystallography, we now report a unified picture that explains the scattered and often inconsistent results obtained with 3(5)-aminopyrazole derivatives and other related molecules...
September 20, 2017: Journal of Organic Chemistry
Jiandong Wang, Shichong Jia, Kenta Okuyama, Zhongyan Huang, Etsuko Tokunaga, Yuji Sumii, Norio Shibata
A novel pentafluorobenzenesulfonyl hypervalent iodonium ylide 3 was designed and synthesized as a useful tool for the preparation of sulfur pentafluorophenyl compounds containing a C6F5S or C6F5SO2 unit. Electrophilic pentafluorophenylthiolation of enamines, formal [3+2] cycloaddition reaction of nitriles and alkynes, and intramolecular SNAr cyclization were achieved using iodonium ylide 3. The fluoro-click reaction was also demonstrated using one of the products via an intermolecular SNAr reaction with heterocentered nucleophiles...
September 20, 2017: Journal of Organic Chemistry
Apurba R Sahoo, Gummidi Lalitha, V Murugesh, Christian Bruneau, Gangavaram V M Sharma, Surisetti Suresh, Mathieu Achard
An efficient and green route to access diverse functionalized ketones via dehydrogenative-dehydrative cross-coupling of primary and secondary alcohols is demonstrated. Selective and tunable formation of ketones or alcohols is catalyzed by a recently developed proton responsive ruthenium phosphine-pyridone complex. Light alcohols such as ethanol could be used as alkylating agents in this methodology. Moreover, selective tandem double alkylation of isopropanol is achieved by sequential addition of different alcohols...
September 20, 2017: Journal of Organic Chemistry
Tetsuo Iwanaga, Tomokazu Yamauchi, Shinji Toyota, Shuichi Suzuki, Keiji Okada
We designed an azacyclophane comprising 3,6-substituted carbazole and 9,10-anthrylene units to investigate the unique electronic properties of the oxidation states arising from the presence of multiple oxidizable azacyclophane. This compound and its analogue containing 1,4-phenylene in substitution of 9,10-anthrylene units were synthesized by Buchwald-Hartwig coupling reactions. Cyclic voltammograms of both the 9,10-anthrylene and 1,4-phenylene derivatives exhibited four quasi-reversible oxidation processes...
September 20, 2017: Journal of Organic Chemistry
Hong-Lei Li, Xiao-Ming Li, Attila Mándi, Sándor Antus, Xin Li, Peng Zhang, Yang Liu, Tibor Kurtán, Bin-Gui Wang
Four new cladosporol derivatives, cladosporols F-I (1-4), the known cladosporol C (5), and its new epimer, cladosporol J (6), were isolated and identified from the marine algal-derived endophytic fungus Cladosporium cladosporioides EN-399. Their structures were determined by detailed interpretation of NMR and MS data, and the absolute configurations were established on the basis of TDDFT-ECD and OR calculations. The configurational assignment of cladosporols F (1) and G (2) showed that the previously reported absolute configuration of cladosporol A and all the related cladosporols need to be revised from (4'R) to (4'S)...
September 20, 2017: Journal of Organic Chemistry
Meng-Yang Chang, Han-Yu Chen, Heui-Sin Wang
We report herein the AgNO2/Pd(PPh3)4-promoted regiocontrolled o-nitration of α-sulfonylmethyl styrenes in MeNO2 with good yields. The o-nitration process provides a series of sulfonyl o-nitrostyrenes. Substituted α-sulfonylmethyl styrenes were synthesized from ZnI2-mediated sulfonylation of substituted α-methylstyrenes and sodium sulfinates (RSO2Na) in MeCN with good to excellent yields. The structures of the key products were confirmed by X-ray crystallography. A plausible mechanism has been proposed herein...
September 19, 2017: Journal of Organic Chemistry
James R Donald, Richard John Kenneth Taylor, Wade F Petersen
A new low-temperature procedure for the synthesis of 3,3-disubstituted 2-oxindoles via cross dehydrogenative coupling (CDC) is reported. The use of a strong, non-reversible base in these reactions has been found to effect a dramatic drop in reaction temperature (to room temperature) relative to the current state-of-the-art (>100 °C). When employing iodine as an 'oxidant', new evidence suggests that this transformation may occur via a transiently stable iodinated intermediate rather than by direct single-electron oxidation...
September 19, 2017: Journal of Organic Chemistry
Chun-Tian Li, Hui Liu, Yan-Jun Xu, Chong-Dao Lu
Diastereoselective aldol reaction of N-tert-butanesulfinyl imidates under typical hard enolization conditions is reported. Potassium bis(trimethylsilyl)amide (KHMDS) effectively promotes the aldol reaction of α-aryl- and α-alkyl-substituted imidates, providing anti-aldol adducts in high yields with good to excellent diastereoselectivities. In the case of α-aryl imidates, high conversion depends on adding trimethylsilyl chloride (TMSCl) to the reaction mixture. In the presence of a suitable Lewis acid, cyclohexanone is a good electrophile in the aldol reaction of imidates...
September 19, 2017: Journal of Organic Chemistry
Chen Yang, Xiao-Song Xue, Jia-Lu Jin, Xin Li, Jin-Pei Cheng
No abstract text is available yet for this article.
September 19, 2017: Journal of Organic Chemistry
Muhammet Uyanik, Takeshi Yasui, Kazuaki Ishihara
Highly enantioselective oxidative dearomatization of 2-naphthol derivatives was achieved for the first time by using conformationally flexible organoiodine catalysts derived from 2-aminoalcohol as a chiral source. Moreover, with the use of these catalysts, excellent enantioselectivities were also achieved for 1-naphthol derivatives, which had previously been obtained with only lower enantioselectivities. Furthermore, the product obtained from the present reaction could be transformed to a highly functionalized spirolactone in high yield and with excellent stereoselectivity...
September 19, 2017: Journal of Organic Chemistry
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