14320-38-8Relevant articles and documents
Practical Olefin Metathesis in Protic Media under an Air Atmosphere
Connon, Stephen J.,Rivard, Michael,Zaja, Mirko,Blechert, Siegfried
, p. 572 - 575 (2003)
The discovery that efficient olefin metathesis reactions involving previously challenging terminal olefin substrates are possible using novel and readily available catalyst systems in non-distilled, non-degassed protic media in air is reported.
Regioselective Chromatic Orthogonality with Light-Activated Metathesis Catalysts
Levin, Efrat,Mavila, Sudheendran,Eivgi, Or,Tzur, Eyal,Lemcoff, N. Gabriel
, p. 12384 - 12388 (2015)
The ability to selectively guide consecutive chemical processes towards a preferred pathway by using light of different frequencies is an appealing concept. Herein we describe the coupling of two photochemical reactions, one the photoisomerization and consequent activation of a sulfur-chelated latent olefin-metathesis catalyst at 350nm, and the other the photocleavage of a silyl protecting group at 254nm. Depending on the steric stress exerted by a photoremovable neighboring chemical substituent, we demonstrate the selective formation of either five- or six-membered-ring frameworks by light-triggered ring-closing metathesis. The orthogonality of these light-induced reactions allows the initiation of these processes independently and in interchangeable order, according to the wavelength of light used to promote them. A guiding light: By the combination of a light-activated sulfur-chelated olefin-metathesis catalyst with a photocleavable bulky silyl protecting group, two orthogonal pathways enabled the selective synthesis of five- or six-membered heterocycles according to the order in which the starting material was irradiated with light of different wavelengths. Thus, protecting-group removal and metathesis gave either a dihydropyran or a dihydrofuran.
Crandall et al.
, p. 423 (1968)
Making JP-10 Superfuel Affordable with a Lignocellulosic Platform Compound
Li, Guangyi,Hou, Baolin,Wang, Aiqin,Xin, Xuliang,Cong, Yu,Wang, Xiaodong,Li, Ning,Zhang, Tao
, p. 12154 - 12158 (2019)
The synthesis of renewable jet fuel from lignocellulosic platform compounds has drawn a lot of attention in recent years. So far, most work has concentrated on the production of conventional jet fuels. JP-10 is an advanced jet fuel currently obtained from fossil energy. Due to its excellent properties, JP-10 has been widely used in military aircraft. However, the high price and low availability limit its application in civil aviation. Here, we report a new strategy for the synthesis of bio-JP-10 fuel from furfuryl alcohol that is produced on an industrial scale from agricultural and forestry residues. Under the optimized conditions, bio-JP-10 fuel was produced with high overall carbon yields (≈65 %). A preliminary economic analysis indicates that the price of bio-JP-10 fuel can be greatly decreased from ≈7091 US$/ton (by fossil route) to less than 5600 US$/ton using our new strategy. This work makes the practical application of bio-JP-10 fuel forseeable.
A concise synthesis of (-)-centrolobine via a diastereoselective ring rearrangement metathesis-isomerisation sequence
Boehrsch, Verena,Blechert, Siegfried
, p. 1968 - 1970 (2006)
A total synthesis of (-)-centrolobine (1) based on a diastereoselective ring rearrangement metathesis-double bond isomerisation sequence and a one-pot cross metathesis-hydrogenation procedure is described. The Royal Society of Chemistry 2006.
A radical clock investigation of microsomal cytochrome P-450 hydroxylation of hydrocarbons. Rate of oxygen rebound
Bowry, Vincent W.,Ingold
, p. 5699 - 5707 (1991)
A number of alkyl-substituted cyclopropanes for which the rates of ring opening of the corresponding cyclopropylcarbinyl radicals have been determined (see preceding paper in this issue) have been used as substrates for hydroxylation by phenobarbital-induced, rat liver microsomal cytochrome P-450 at 37 °C. Three of these compounds gave both ring-closed and ring-opened alcohols, thus allowing the rate constant, kOH, for "oxygen rebound" onto the corresponding carbon-centered radicals to be determined. In particular, both trans- (1bH) and cis- (1cH) 1,2-dimethylcyclopropane gave 4-penten-2-ol (2bOH) and 2-methyl-3-buten-1-ol (3bOH) together with the corresponding trans- (1bOH) or cis- (1cOH) 2-methylcyclopropanemethanols. Of much greater importance, for both 1bH and 1cH the ratios of the yields of the secondary-to-primary ring-opened alcohols, i.e., [2bOH]/[3bOH], were the same, within experimental error as the ratio of the rates of ring opening of the corresponding trans- (1b?) and cis- (1c?) methylcyclopropylmethyl radicals in solution at 37 °C. This indicates that when 1b? and 1c? are formed from their parent hydrocarbons by H-atom abstraction in the hydrophobic pocket of cytochrome P-450 they are not detectably constrained in their subsequent reactions by their unusual environment. From the ratio of the yields of the unrearranged alcohol to each of the rearranged alcohols we calculate kOH values of 1.5 and 1.6 × 1010 s-1 for 1bH as substrate and values of 1.9 and 1.8 × 1010 s-1 for 1cH as substrate. Consistent with these values we have obtained kOH = 2.2 × 1010 s-1 for bicyclo[2.1.0]pentane as substrate. Substrates such as methylcyclopropane and 1,1-dimethylcyclopropane, for which the corresponding cyclopropylmethyl radicals undergo relatively slow ring opening, yielded only the ring-closed alcohols on oxidation with cytochrome P-450. 1,1,2,2-Tetramethylcyclopropane gave only a trace of a ring-opened alcohol, corresponding to kOH = 2.5 × 1011 s-1 for this substrate. Hexamethylcyclopropane gave no detectable ring-opened alcohol from which observation a limit for kOH > 5 × 1011 s-1 can be calculated. Possible explanations for the unexpected behavior of these last two, relatively bulky, substrates are discussed.
Coordination chemistry of a hemilabile amino-tethered N-heterocyclic carbene with ruthenium(II)
Jong, Howard,Patrick, Brian O.,Fryzuk, Michael D.
, p. 2333 - 2341 (2011)
The reaction of the amine-tethered N-heterocyclic carbene ligand 2,4,6-Me3C6H2NC3H 2NCH2CH2NH-2,4,6-Me3C 6H2 (Mes[CNH]) with Ru(CHPh)(PCy 3)2Cl2 leads to the formation of Mes[CNH]Ru(CHPh)(PCy3)Cl2, which exists as a mixture of two isomers in a ratio of 7:1. While the major species was characterized by X-ray crystallography, the minor rotamer species could be characterized only in solution. Phosphine exchange kinetics and equilibrium variable-temperature measurements did not show much difference from benchmark Grubbs systems. Evidence for coordination of the amine tether was obtained by addition of pyridine, which generated the octahedral complex Mes[CNH]Ru(CHPh)(py)Cl2 with the tethered amine coordinated. Similarly, addition of PMe3 results in the formation of Mes[CNH]Ru(CHPh)(PMe3)Cl2, also having an octahedral structure with the pendant amine ligated. Attempts to benchmark the catalytic potential of the PCy3 derivative showed that it was far inferior to known Grubbs-type systems.
Organocatalytic Desymmetrization of Meso-Aziridines Via Asymmetric Intramolecular Rearrangement
Costanzo, Martina,Cortigiani, Mauro,Gillick-Healy, Malachi W.,Kelly, Brian G.,Monasterolo, Claudio,Adamo, Mauro F. A.
, p. 4560 - 4565 (2021/07/20)
Herein we report the first organocatalytic method for the desymmetrization of meso-aziridines that does not require the use of an external nucleophilic reagent. The process was designed upon a base promoted rearrangement of bicyclic meso-cyclopentanone aziridines, that progresses in intramolecular fashion to provide densely functionalized cyclic ketones, key intermediates for the preparation of Active Pharmaceutical Ingredients. The key enantio-determining step proceeded under the catalysis of a bifunctional thiourea organocatalyst. The process provides an entry to a class of highly functionalized chiral amines, 4-aminocyclopentenones, not accessible with previous desymmetrization methods. The ambiphilic nature of the products makes them versatile synthetic intermediates in the preparation of natural products and popular antiviral nucleoside inhibitors, for example abacavir.
4-Aminocyclopentane-1,3-diols as platforms for diversity: Synthesis of a screening library
Zohrabi-Kalantari,Wilde,Grünert,Bednarski,Link
, p. 203 - 213 (2014/03/21)
Trisubstituted cyclopentanes have a discrete shapely curvature. While the central ring of these compounds is devoid of rotatable bonds, the pseudo rotation of the cyclopentane ring leads to a desirable disruption of planarity. This is favorable for aqueous solubility and enables addressing of wide-ranging conformational space. The sp3-rich framework of 4-aminocyclopentane- 1,3-diols offers stereochemically defined attachment points for substituents and renders these fragment-like molecules good platforms for molecular diversity. By using an established N-selective polymer-assisted acylation protocol, these scaffolds with natural product-like properties were transformed into a screening library by attachment of substituents at defined positions. Here we describe the synthesis and characterization of these molecular platforms and their use as starting points for the construction of an 80-member library of 4-amidocyclopentane-1,3-diol monoethers. Five of the compounds displayed cytotoxicity in a tumor cell line assay with IC50 values in the low micromolar range.
