18495-26-6Relevant articles and documents
Palladium(II)-catalyzed carbocyclization: Vinylpalladium in 1,4-oxidation of conjugated dienes
Nilsson, Ylva I. M.,Gatti, Roberto G. P.,Andersson, Pher G.,Baeckvall, Jan-E.
, p. 7511 - 7523 (1996)
Palladium-catalyzed 1,4-oxidation of conjugated dienes involving carbon-carbon bond formation has been realized. The reaction is performed with both acyclic and cyclic dienes with a carbon chain containing a terminal or internal triple bond. A vinylpalladium species formed by chloropalladation of the alkyne inserts one of the double bonds of the diene in a Heck-type reaction. The addition of palladium and chloride over the triple bond is non-stereoselective while the overall 1,4-addition by carbon and chloride over the diene is highly stereoselective and occurs anti. The stereoselectivity of the chloropalladation is dependent on the chloride concentration and varies with the substrate.
Palladium-catalyzed cyclization of alkynoic acids to form vinyl dioxanones bearing a quaternary allylic carbon
Ogiwara, Yohei,Sato, Kazuya,Sakai, Norio
supporting information, p. 5296 - 5299 (2017/11/06)
A palladium-catalyzed intramolecular reaction of carboxylic acids and alkynes in a novel cyclization manner was developed. This unique cyclization efficiently provided a wide range of complex ring systems-vinyl dioxanones bearing a quaternary allylic carbon. Mechanistic studies suggest an allenyl carboxylate as an intermediate.
Iodocyclization of hydroxylamine derivatives based on the control of oxidative aromatization leading to 2,5-dihydroisoxazoles and isoxazoles
Okitsu, Takashi,Sato, Kana,Potewar, Taterao M.,Wada, Akimori
experimental part, p. 3438 - 3449 (2011/06/26)
An efficient method for the synthesis of 2,5-dihydroisoxazoles and isoxazoles using iodocyclization of N-alkoxycarbonyl O-propargylic hydroxylamines has been developed. 2,5-Dihydro-4-iodoisoxazole underwent the cross-coupling reactions without aromatization to afford polyfunctionalized 2,5-dihydroisoxazoles. This process was applied to the preparation of valdecoxib and its 2,5-dihydro-derivative.
Synthesis of carbazoles by gold(I)-catalyzed carbocyclization of 2-(enynyl)indoles
Praveen, Chandrasekaran,Perumal, Paramasivan Thirumalai
scheme or table, p. 521 - 524 (2011/04/17)
A new synthetic protocol for carbazoles through gold(I)-catalyzed intramolecular hydroarylation of (Z)-2-(enynyl)indoles was achieved in good yields. The requisite (Z)-2-(enynyl)indoles were synthesized stereoselectively by trimethylgallium-promoted, Z-selective Wittig olefination of N-alkylindole-2-carboxaldehydes with propargyl ylides. Substrates possessing both alkyl as well as aromatic groups are well tolerated under these reaction conditions. Georg Thieme Verlag Stuttgart.
Efficient control for the cationic platinum(II)-catalyzed concise synthesis of two types of fused carbocycles with angular oxygen functionality
Kusama, Hiroyuki,Watanabe, Eiichi,Ishida, Kento,Iwasawa, Nobuharu
supporting information; experimental part, p. 2273 - 2277 (2012/06/30)
Double trouble: An efficient method for the preparation of two types of synthetically useful bicyclo[5.4.0]undecanes with an angular oxygen functionality was realized starting from easily available substrates; this method was based on the [3+2] cycloaddit
Asymmetric synthesis of α-allenylglycines
Bucuroaia, Carmen,Groth, Ulrich,Huhn, Thomas,Klinge, Michael
experimental part, p. 3605 - 3612 (2009/12/01)
The coupling of the homocuprate of the bislactim ether of cyclo-(-L-Val-Gly-) (9) with primary propargyl halides produces the allenyl-substituted bislactim ethers 11 in a highly diastereoselective manner, whereas the alkylation of the lith-iated bislactim ether of cyclo-(-L-Val-Gly-) yields the proparg-yl-substituted bislactim ethers 12. Subsequent hydrolysis affords, after protection of the amino group, the methyl α- allenylglycinates 15, the α-allenylglycines 16, and the methyl α-propargylglycinates 17.
A facile and regioselective synthesis of 2,5-disubstituted pyrroles via gold-catalyzed cycloisomerization of acetylenylaziridines
Chen, Dong-Dong,Hou, Xue-Long,Dai, Li-Xin
supporting information; experimental part, p. 6944 - 6946 (2010/02/27)
Gold-catalyzed cycloisomerization reaction of acetylenylaziridines provides 2,5-disubstituted pyrroles in high yields. The presence of protic species accelerates the reaction rate and improves the yields of pyrrole products.
Covalent modification of cyclooxygenase-2 (COX-2) by 2-acetoxyphenyl alkyl sulfides, a new class of selective COX-2 inactivators
Kalgutkar, Amit S.,Kozak, Kevin R.,Crews, Brenda C.,Hochgesang Jr., G. Phillip,Marnett, Lawrence J.
, p. 4800 - 4818 (2007/10/03)
All of the selective COX-2 inhibitors described to date inhibit the isoform by binding tightly but noncovalently at the substrate binding site. Recently, we reported the first account of selective covalent modification of COX-2 by a novel inactivator, 2-acetoxyphenyl hept-2-ynyl sulfide (70) (Science 1998, 280, 1268-1270). Compound 70 selectively inactivates COX-2 by acetylating the same serine residue that aspirin acetylates. This paper describes the extensive structure-activity relationship (SAR) studies on the initial lead compound 2-acetoxyphenyl methyl sulfide (36) that led to the discovery of 70. Extension of the S-alkyl chain in 36 with higher alkyl homologues led to significant increases in inhibitory potency. The heptyl chain in 2-acetoxyphenyl heptyl sulfide (46) was optimum for COX-2 inhibitory potency, and introduction of a triple bond in the heptyl chain (compound 70) led to further increments in potency and selectivity. The alkynyl analogues were more potent and selective COX-2 inhibitors than the corresponding alkyl homologues. Sulfides were more potent and selective COX-2 inhibitors than the corresponding sulfoxides or sulfones or other heteroatom-containing compounds. In addition to inhibiting purified COX-2, 36, 46, and 70 also inhibited COX-2 activity in murine macrophages. Analogue 36 which displayed moderate potency and selectivity against purified human COX-2 was a potent inhibitor of COX-2 activity in the mouse macrophages. Tryptic digestion and peptide mapping of COX-2 reacted with [1-14C-acetyl]-36 indicated that selective COX-2 inhibition by 36 also resulted in the acetylation of Ser516. That COX-2 inhibition by aspirin resulted from the acetylation of Ser516 was confirmed by tryptic digestion and peptide mapping of COX-2 labeled with [1- 14C-acetyl]salicyclic acid. The efficacy of the sulfides in inhibiting COX- 2 activity in inflammatory cells, our recent results on the selectivity of 70 in attenuating growth of COX-2-expressing colon cancer cells, and its selectivity for inhibition of COX-2 over COX-1 in vivo indicate that this novel class of covalent modifiers may serve as potential therapeutic agents in inflammatory and proliferative disorders.
Preparation of 2-iodo-1,3-butadienes from 1-trimethylsilyl-2,3- butadienes and their functionalizations
Nishiyama, Takashi,Esumi, Tomoyuki,Iwabuchi, Yoshiharu,Irie, Hiroshi,Hatakeyama, Susumi
, p. 43 - 46 (2007/10/03)
Successive treatment of 1-trimethylsilyl-2.3-butadienes with iodine and tetra-n-butylammonium fluoride in the same flask affords 2-iodo-1.3- butadienes in good yields and their palladium-catalyzed carbonylation and alkynylation allows introduction of este
Synthesis of lysophosphatidylserine with 19:4 acyl group, as a novel sodium-potassium ATPase inhibitor, in relation to DLIS-2, an endogenous digoxin-like substance
Inami,Teshima,Emura,Shiba
, p. 4033 - 4036 (2007/10/02)
A lysophosphatidylserine with 19:4 acyl group proposed as a candidat of DLIS-2, an endogenous digoxin-like substance was chemically synthesized. The synthetic compound showed a significant activity of Na+,K+-ATPase inhibition, which has been accepted as a major indicator activity for the essential hypertension.
