110202-07-8Relevant articles and documents
HYDROGENATION OF CARBONYLS WITH TETRADENTATE PNNP LIGAND RUTHENIUM COMPLEXES
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Page/Page column 27; 36, (2019/10/04)
The present invention relates to catalytic hydrogenation processes, using Ru complexes with tetradentate ligands of formula L in hydrogenation processes for the reduction of ketone, aldehyde, ester or lactone into the corresponding alcohol or diol respectively. The described processes use a ruthenium complex of the formula (1) as defined below, and where the ligand (L) is defined by the Markush formula shown above.
Synthesis of (+)-manoalide via a copper(I)-mediated 1,2-metalate rearrangement
Pommier, Agnès,Stepanenko, Viatcheslav,Jarowicki, Krzysztof,Kocienski, Philip J.
, p. 4008 - 4013 (2007/10/03)
An enantiospecific synthesis of the phospholipase A2 inhibitor (+)-(4R)-manoalide is reported in which all 25 carbons of the sesterterpenoid skeleton are constructed from 3-furaldehyde, trimethylalane, oxirane, CO, β-ionone, and propargyl bromide. The overall yield for the longest linear sequence (12 steps) is 12%. Key steps include (a) a zirconium-catalyzed carboalumination reaction to construct the C10-C11 trisubstituted alkene, (b) a Cu(I)-mediated 1,2-metalate rearrangement to construct the C6-C7 trisubstituted alkene, (c) a Sharpless kinetic resolution to secure the (4R)-stereochemistry, (d) generation of a 5-stannyl-2,3-dihydrofuran by Mo-catalyzed cycloisomerization of a homopropargylic alcohol, and (e) construction of the hydroxyfuranone ring by photooxidation of a silylfuran.
Two Syntheses of Manoalide via Heteroatom-Assisted Alkyne Carbometallation
Bury, Paul,Hareau, Georges,Kocienski, Philip,Dhanak, Dashyant
, p. 8793 - 8808 (2007/10/02)
Two approaches to the sesterterpenoid phospholipase A2 inhibitors seco-manoalide (3) and manoalide (1) are described based on carbometallation of propargylic alcohols to generate the functionalised C6-C7 trisubstituted alkene.Both syntheses also deploy the photooxidation of a furan in order to generate a 4-substituted 5-hydroxy-2(5H)-furanone moiety.
Internal Nucleophilic Termination in Biomimetic Acid Mediated polyene Cyclizations: Stereochemical and Mechanistic Implications. Synthesis of (+/-)-Ambrox and Its Diastereoisomers
Snowden, Roger L.,Eichenberger, Jean-Claude,Linder, Simon M.,Sonnay, Philippe,Vial, Christian,Schulte-Elte, Karl H.
, p. 955 - 960 (2007/10/02)
Treatment of 10 structurally releted trienols and dienols 5-8 with an excess of fluorosulfonic acid in 2-nitropropane at -90 deg C afforded, in 74-87percent yield, diastereoisomeric mixtures of the odoriferous norlabdane oxides 9-15 ((-)-9 (Ambrox) is a naturally occuring ambergris odorant).These tranformations represent examples of efficientbiomimetic acid-mediated cyclizations in which the hydroxyl group serves as the internal nucleophilic terminator.The stereochemical outcome of these kinetically controlled processes has been analysed in detail, and mechanistic hypotheses consistent with the results have been proposed.For the four acyclic trienols 5, the major reaction pathway can be rationalized by a totally synchronous process involving three internal anti additions via chair or skew-boat conformations of the nascent cyclohexane rings.An alternative explanation postulates a nonsynchronous process in which ring closure to an intermediate cyclohexyl cation is followed by rapid cyclization, directed by a strong kinetic preference for equatorial C-C and C-O bond formation.In contrast, for the monocyclic dienols 6-8 only a nonsynchronous process, involving prior protonation of the cyclohexenyl bond, is fully consisitent with the results.In the nonsynchronous processes, the orientation of the side chain vicinal to the cyclohexyl cation directs the stereochemical course of the cyclization.For the acyclic trienols, this factor is predetermined by the configuration of the C(7)=C(8) bond, whereas, for the monocyclic dienols, this orientation is determined by the stereoselective axial protonation of the cyclohexenyl bond in 6, or by the distribution of cyclohexene and cyclohexane conformers in 7 and 8, respectively.In the cases studied, it is clear that conformational inversion of the six-membered ring is slower than cyclization and thus ensures that an equatorial side chain leads to a trans A/B ring junction in the cyclization product, whereas an axial side chain affords a cis A/B ring junction.
SYNTHESIS OF (S)-MANOALIDE DIOL AND THE ABSOLUTE CONFIGURATION OF NATURAL MANOALIDE
Amoo, Victor Ekow,Bernardo, Silvano De,Weigele, Manfred
, p. 2401 - 2404 (2007/10/02)
A synthesis of (S)-manoalide diol (2a) has been achieved using 2-deoxy-D-ribose as starting material to unequivocally supply the stereochemistry.Reduction of natural manoalide afforded enantiomeric manoalide diol 2b.Thus, the absolute configuration of man
