123669-93-2Relevant articles and documents
Model studies for the synthesis of galbonolide B
Eshelby, James,Goessman, Matthias,Parsons, Philip J.,Pennicott, Lewis,Highton, Adrian
, p. 2994 - 2997 (2005)
The construction of the fourteen membered ring present in galbonolide B 1 is reported. The 10,11-diene system present in the southern portion of 1 has been constructed using an ester enolate rearrangement/silicon mediated fragmentation cascade, whilst the macrocycle has been synthesised following a Johnson rearrangement/mercury assisted ring closure protocol. The Royal Society of Chemistry 2005.
Exploration of chiral induction on epoxides in lipase-catalyzed epoxidation of alkenes using (2R,3S,4R,5S)-(-)-2,3:4,6-di-O-isopropylidiene-2-keto-l-gulonic acid monohydrate
Sarma, Kuladip,Goswami, Amrit,Goswami, Bhabesh C.
experimental part, p. 1295 - 1300 (2009/10/17)
Epoxidation of alkenes by peracid, generated in situ from (2R,3S,4R,5S)-(-)-2,3:4,6-di-O-isopropylidiene-2-keto-l-gulonic acid monohydrate [(-)-DIKGA] and hydrogen peroxide by lipase catalysis induces chirality on the product epoxides with moderate to good enantioselectivity (35-71%). Alkoxy/aralkyloxy styrenes however did not undergo any epoxidation. (R)-(+)-4-Hydroxy styrene-7,8-oxide was formed and isolated with moderate enantiomeric excess (57%) but was found to have poor stability.
Stereoselective formal total synthesis of (+)-methynolide
Yadav,Pratap,Rajender
, p. 5882 - 5885 (2008/02/09)
(Chemical Equation Presented) A highly stereoselective and convergent formal total synthesis of (+)-methynolide is described. The salient features of this synthesis have been the construction of the C1-C7 and C8-C11fragments via a desymmetrization approach, Sharpless asymmetric epoxidation of an allyl alcohol, respectively, and linkage of both the fragments by Nozaki-Hiyama-Kishi reaction.
A formal stereoselective synthesis of (-)-maurenone
Yadav,Ravindar,Reddy
, p. 1957 - 1959 (2008/03/28)
An efficient formal synthesis of marine polypropionate (-)-maurenone is described. Highlights of the strategy include the utilization of a desymmetrization technique and the activation of the epoxide oxygen with a silyl triflate followed by intramolecular hydride transfer - a novel transformation. Georg Thieme Verlag Stuttgart.
Process for the preparation of substituted pyrrolidine neuraminidase inhibitors
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, (2008/06/13)
A process for the preparation of neuraminidase inhibitors having structural formula (28) or therapeutically acceptable salts thereof, in which R1 is alkyl, cycloalkyl, cycloalkylalkyl, or arylalkyl; R2 is alkyl, cycloalkyl, cycloalky
Five-membered carbocyclic and heterocyclic inhibitors of neuraminidases
-
, (2008/06/13)
Disclosed are compounds of the formula: which are useful for inhibiting neuraminidases from disease-causing microorganisms, especially, influenza neuraminidase. Also disclosed are compositions and methods for preventing and treating diseases caused by microorganisms having a neuraminidase, processes for preparing the compounds and synthetic intermediates used in these processes.
Enantioselective synthesis of antiinfluenza compound A-315675
DeGoey, David A.,Chen, Hui-Ju,Flosi, William J.,Grampovnik, David J.,Yeung, Clinton M.,Klein, Larry L.,Kempf, Dale J.
, p. 5445 - 5453 (2007/10/03)
Drug discovery efforts at Abbott Laboratories have led to the identification of influenza neuraminidase inhibitor A-315675 (1) as a candidate for development as an antiinfluenza drug. A convergent, stereoselective synthesis of this highly functionalized pyrrolidine is reported that utilizes pyrrolinone 2 as the key intermediate. The C5, C6 stereochemistry was established through a diastereoselective condensation of chiral imine compound 3 with silyloxypyrrole 4 to give pyrrolinone 2. The stereochemical outcome of this reaction depended critically on the choice of the imine functional group (FG), with tritylsulfenyl and (R)-toluenesulfinyl providing the desired products in good yields as crystalline intermediates. Conversion of pyrrolinone 2 into 1 was accomplished in seven subsequent steps, including Michael addition of cis-1-propenylcuprate at C4 and introduction of a cyano group as a carboxylic acid equivalent at C2.
Design of optically active hydroxamic acids as ligands in vanadium- catalyzed asymmetric epoxidation
Hoshino, Yujiro,Murase, Noriaki,Oishi, Masataka,Yamamoto, Hisashi
, p. 1653 - 1658 (2007/10/03)
New optically active hydroxamic acids bearing a 1,1'-binaphthyl group were prepared as ligands in a vanadium-catalyzed asymmetric epoxidation. The feature of these hydroxamic acids is a sterically hindered ligand. The asymmetric epoxidation with good selectivity and reactivity can be established by using VO(O-i-Pr)3 (5 mol%) and a small excess amount of ligand (7.5 mol%) with triphenylmethyl hydroperoxide (TrOOH) in toluene at - 20 °C. Disubstituted allyl alcohols were epoxidized more rapidly than mono- or tri-substituted allyl alcohols, and were obtained in good to high enantioselectivities (48 - 94%ee). The transition state based on X-ray crystal structure of 1e is discussed.
A pH Study on the Chiral Ketone Catalyzed Asymmetric Epoxidation of Hydroxyalkenes
Wang, Zhi-Xian,Shi, Yian
, p. 3099 - 3104 (2007/10/03)
A detailed study shows that the chiral ketone catalyzed asymmetric epoxidations of hydroxyalkenes are highly pH dependent. The lower enantioselectivity obtained at low pH is attributed to the substantial contribution of the direct epoxidation by Oxone. At high pH the epoxidation mediated by chiral ketone out-competes the racemic epoxidation, leading to higher enantioselectivity. The effective substrates include allylic alcohol, homoallylic alcohol, and bishomoallylic alcohol. In most cases, over 90% ee was obtained.
Highly Regio- and Enantioselective Monoepoxidation of Conjugated Dienes
Frohn, Michael,Dalkiewicz, Molly,Tu, Yong,Wang, Zhi-Xian,Shi, Yian
, p. 2948 - 2953 (2007/10/03)
This paper describes a highly effective and mild asymmetric monoepoxidation method for conjugated dienes using a fructose-derived chiral ketone 1 as catalyst and Oxone as oxidant. The regioselectivies and enantioslectivies are very high in most cases. For unsymmetrical dienes, the regioselectivity can be regulated by using steric and electronic control. The olefin substrates include trans-disubstituted and trisubstituted olefins that can bear a wide range of functional groups such as hydroxyl groups, TBS ethers, or esters. The enantiomeric excesses for the major monoepoxides range from 89% to 97%. The epoxidation is believed to proceed via a spiro mode.
