- Pd(OAc)2-catalyzed orthogonal synthesis of 2-hydroxybenzoates and substituted cyclohexanones from acyclic unsaturated 1,3-carbonyl compounds
-
A Pd-catalyzed orthogonal synthesis of substituted 2-hydroxybenzoates and substituted cyclohexanones was developed for the first time. The substituted 2-hydroxybenzoates were obtained from acyclic unsaturated 1,3-carbonyl compounds using a combination of catalytic Pd(OAc)2 and Cu(OAc)2. On the other hand, the substituted cyclohexanones were produced from similar substrates via catalytic Pd(OAc)2 and hydrogen chloride. Each transformation was clean, easy to work up, provided the desired compounds in good purities, and did not require column chromatography purification.
- Miyagi, Toshinori,Okada, Sho,Tada, Naoya,Sugihara, Masahiro,Kagawa, Natsuko,Takabatake, Tetsuhiko,Toyota, Masahiro
-
supporting information
p. 1653 - 1657
(2019/05/29)
-
- Ruthenium(II)-catalyzed synthesis of hydroxylated arenes with ester as an effective directing group
-
An unprecedented Ru(II) catalyzed ortho-hydroxylation has been developed for the facile synthesis of a variety of multifunctionalized arenes from easily accessible ethyl benzoates with ester as an efficient directing group. Both the TFA/TFAA cosolvent system and oxidants serve as the critical success factors in this transformation. The reaction demonstrates excellent reactivity, good functional group tolerance, and high yields.
- Yang, Yiqing,Lin, Yun,Rao, Yu
-
supporting information; experimental part
p. 2874 - 2877
(2012/07/28)
-
- Enediyne antitumor antibiotic maduropeptin biosynthesis featuring a C-methyltransferase that acts on a COA-Tethered aromatic substrate
-
The enediyne antitumor antibiotic maduropeptin (MDP) is produced by Actinomadura madurae ATCC 39144. The biosynthetic pathway for the 3,6-dimethylsalicylic acid moiety of the MDP chromophore is proposed to be comprised of four enzymes: MdpB, MdpB1, MdpB2, and MdpB3. Based on the previously characterized biosynthesis of the naphthoic acid moiety of neocarzinostatin (NCS), we expected a biosynthetic pathway featuring carboxylic acid activation by the MdpB2 CoA ligase immediately before its coupling to an enediyne core intermediate. Surprisingly, the MDP aromatic acid biosynthetic pathway employs an unusual logic in which MdpB2-catalyzed CoA activation occurs before MdpB1-catalyzed C-methylation, demonstrating that MdpB1 is apparently unique in its ability to C-methylate a CoA-tethered aromatic acid. MdpB2 is a promiscuous CoA ligase capable of activating a variety of salicylic acid analogues, a property that could be potentially exploited to engineer MDP analogues.
- Ling, Jianya,Horsman, Geoffrey P.,Huang, Sheng-Xiong,Luo, Yinggang,Lin, Shuangjun,Shen, Ben
-
supporting information; experimental part
p. 12534 - 12536
(2010/11/04)
-
- The total synthesis of coleophomones B, C, and D
-
Members of the coleophomone family of natural products all possess several intriguing and challenging architectural features, as well as exhibit unusual biological activity. They, therefore, constitute attractive targets for synthesis. In this Article, we describe the total synthesis of coleophomones B (2), C (3), and D (4). The highly strained and congested 11-membered macrocycle of coleophomones B (2) and C (3) was constructed using an impressive olefin metathesis reaction. Furthermore, both of the requisite geometric isomers of the Δ within the macrocycle could be accessed from a common precursor, facilitating a divergence that lent the coleophomone B (2)/C (3) synthesis an unusually high degree of efficiency. The synthesis of coleophomone D (4) confirmed that it exists as a dynamic mixture of isomeric forms with a different aromatic substitution pattern from the other family members.
- Nicolaou,Montagnon, Tamsyn,Vassilikogiannakis, Georgios,Mathison, Casey J. N.
-
p. 8872 - 8888
(2007/10/03)
-
- A novel synthesis of bromomethoxy disubstituted derivatives of benzocyclobutenone
-
Flash vacuum pyrolysis of ortho-methyl aromatic acid chlorides has been used to prepare a variety of substituted derivatives of the benzocyclobutenone ring system starting from simple precursors. The significance of the present reaction lies in the fact that the bromine atom present in the aromatic nucleus, remains undisturbed during the high temperature treatment employed in the pyrolysis and forms, a bromomethoxyketone successfully. This is an altogether new approach.
- Barve,Schiess
-
p. 1729 - 1736
(2007/10/03)
-
- Process for the preparation of 5- and/or 6-substituted-2-hydroxybenzoic acid esters
-
There is provided a single-step process for the preparation of a compound of formula I. Compounds of formula I are useful as starting materials in the synthesis of natural products and in the manufacture of benzophenone fungicidal agents.
- -
-
-
- Process for the preparation of 5-and/or 6-substituted-2-hydroxybenzoic acid esters
-
There is provided a single-step process for the preparation of a compound of formula I. Compounds of formula I are useful as starting materials in the synthesis of natural products and in the manufacture of benzophenone fungicidal agents.
- -
-
-
- Process for the preparation of 5- and/or 6-substituted-2-hydroxybenzoic acid esters
-
There is provided a single-step process for the preparation of a compound of formula I. Compounds of formula I are useful as starting materials in the synthesis of natural products and in the manufacture of benzophenone fungicidal agents.
- -
-
-
- A straightforward entry into polyketide monoprenylated furanocoumarins and pyranocoumarins
-
A regioselective synthesis of 5-methyl- and 5-ethyl-4- hydroxycoumarin (1b and 1c, respectively) is described. Starting from these compounds, several prenylated polyketide coumarins of limited availability from natural sources and important taxonomic relevance were prepared.
- Appendino, Giovanni,Cravotto, Giancarlo,Giovenzana, Giovanni B.,Palmisano, Giovanni
-
p. 1627 - 1631
(2007/10/03)
-
- Synthesis of Saturated Anacardic Acids, and Alkenyl and Alkynyl Analogues
-
The C-alkylation of esters of 2-methoxy-6-methylbenzoic acid and of the 4-methyl isomers affords a route to homologous compounds including in the former case members of the natural anacardic acids from Anacardium occidentale and ω-alkynyl compounds suitable for synthesising other natural phenolic lipids or for structure/activity studies.
- Tyman, John H. P.,Visani, Naina
-
p. 228 - 240
(2007/10/03)
-
- Versatile Dehydrogenative Aromatization of α,β-Unsaturated Cyclohexenones with VO(OEt)Cl2-Me3SiOTf
-
An oxovanadium compound obtained from VO(OEt)Cl2 and AgOTf or Me3SiOTf efficiently induced dehydrogenative aromatization of α,β-unsaturated cyclohexenones to give aryl ethyl ethers in good yields.
- Hirao, Toshikazu,Mori, Makoto,Ohshiro, Yoshiki
-
p. 783 - 784
(2007/10/02)
-
- Efficient total synthesis of AI-77-B, a gastroprotective substance from Bacillus pumilus AI-77
-
First total synthesis of AI-77-B (1), a gastroprotective substance from Bacillus pumilus AI-77, was achieved in a stereoselective and convergent manner. In this synthesis, the dihydroisocoumarin part 2 was constructed in one step through 1,2-addition of the benzylic anion 17b to Boc-L-leucinal 7b. The hydroxy amino acid 4 was elaborated from (R)-glutamic acid in a highly stereoselective manner. Condensation of 2·HCl and 4, intramolecular Pinner reaction, followed by mild hydrolysis afforded AI-77-B (1).
- Hamada,Hara,Kawai,Kohno,Shioiri
-
p. 8635 - 8652
(2007/10/02)
-
- Mechanism of Manganese(III)-Based Oxidation of β-Keto Esters
-
The rate-determining step in the oxidation of 2-substituted acetoacetate esters such as 10b by Mn(OAc)3*2H2O is the loss of a proton from the 10b-Mn(III) complex 17b to form 18b.The rate-determining step in the oxidation of 2-unsubstituted acetoacetate esters such as 10a by Mn(OAc)3*2H2O in the presence of an alkene is the oxidation of Mn(III)-10a-alkene complex 20a to give the addition product 21a.In the absence of alkene, a much slower electron transfer from the enolate to the oxo-centered metal system to give 19a is the rate-determining step.Oxidative cyclization of 1b produces oxocyclopentanecarboxylates such as 4b in poor yield since overoxidation of the product occurs at a rate comparable to that of the initial cyclization.Oxidative cyclization of 1a produces oxocyclohexanecarboxylates such as 4a in good yield since the oxidation of 1a is much faster than the oxidation of 1b.Overoxidation can be prevented by oxidative cyclization of 2-chloroacetoacetates such as 30a and 36a followed by zinc reduction to give 32c and 39c in good overall yield.
- Snider, Barry B.,Patricia, Jeffrey J.,Kates, Steven A.
-
p. 2137 - 2143
(2007/10/02)
-
- SYNTHETIC STUDIES ON NOGALAMYCIN CONGENERS ; SYNTHESES AND ANTITUMOR ACTIVITY OF VARIOUS NOGALAMYCIN CONGENERS
-
Various structural types of nogalamycin congeners and their partial structures, which had been previously synthesized in the course of our synthetic studies on the total syntheses or were originally produced by employing the explored synthetic scheme, were subjected to in vitro cytotoxicity and in vivo antitumor activity assay against P388 murine leukemia.These studies obviously disclosed novel aspects of the structure-activity relationships of nogalamycin congeners.
- Matsuda, Fuyuhiko,Kawasaki, Motoji,Ohsaki, Masako,Yamada, Kaoru,Terashima, Shiro
-
p. 5745 - 5760
(2007/10/02)
-