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Archive for the ‘Diastereoselective’ Category

Cram-chelation vs. Felkin-Ahn review

Posted by naturalproductman on May 2, 2011

Patrick Walsh and co-workers have published in JACS on a hydroboration/transmetalation sequence of an alkyne followed by a nucleophilic addition onto a ketone.

hydroboration

JACS paper

Posted in Cascade Reactions, Diastereoselective, Mechanistic, Methodology | Leave a Comment »

Spiro-Fused Indanones

Posted by naturalproductman on January 26, 2011

William Goldring and co-workers at the Queen’s University Belfast in Ireland have published in Tetrahedron Letters on a Diels-Alder reaction – the substrates here are an alpha-methylene indanone dienophile and a diene with a TMS-ether group.

Diels-Alder

 

TL paper

Posted in Cycloaddition, Diastereoselective, Diels-Alder, Methodology, Named Reactions, Pericyclic reactions | Leave a Comment »

(2′R)-2′-Deoxy-2′-C-methyluridine Synthesis

Posted by naturalproductman on December 6, 2010

Sebastian Lemaire and co-workers at Johnson and Johnson Pharmaceuticals have published in JOC on an approach to synthesize a methylated nucleotide from uridine – the trick is to selectively protect the 3′ and 5′ alcohols simultaneously using a TIPDS (1,3-(1,1,3,3)-tetraisopropyldisiloxanylidene) protecting group, which will leave the 2′ hydroxy mostly unprotected.

methyl

 

JOC paper

Posted in Diastereoselective, Methodology, Nucleic acids | Leave a Comment »

Calcium, it’s good.

Posted by naturalproductman on November 5, 2010

Zachary Aron and co-workers from Indiana University have published in JOC on a calcium (II) triflate catalyzed three component coupling approach to access pyrrolidines.

pyrrolidine

 

JOC paper

Posted in Cascade Reactions, Diastereoselective, Methodology, Multi-Component Coupling, Ring forming | Leave a Comment »

Diastereoselective Protonation of Enolates

Posted by naturalproductman on October 2, 2010

If you take an alpha-substituted-alpha,beta-unsaturated aldehyde tethered with a stereoisomerically pure alcohol and put it in the presence of a copper hydride reagent, then you can force it to undergo a diastereoselective protonation of the corresponding enolate that forms.

enolate protonation

ACIEE paper

Posted in Cascade Reactions, Copper, Diastereoselective, Methodology, Transition Metal | Leave a Comment »

Asymmetric Spirocyclization

Posted by naturalproductman on August 2, 2010

Shu-Li You and co-workers at the Shanghai Institute of Organic Chemistry have published in JACS on an iridium catalyzed asymmetric spirocyclization reaction to form spiroindolenines.

spiroindolenines

JACS paper

Posted in Alkaloids, Asymmetric, Diastereoselective, Iridium, Methodology, Spirocycles, Transition Metal | Leave a Comment »

Claisen Rearrangement to Access Chiral Quaternary Carbons

Posted by naturalproductman on June 30, 2010

Derrick Clive and co-worker at the University of Alberta have published in JOC on Claisen rearrangement approach to access a chiral quaternary carbon center.  The stereoselectivity comes from substrate control where the chiral center originates from serine.  The dihydropyran Claisen rearrangement precursor is synthesized from an intramolecular Michael addition of an amine to an alkynone.  The presumed vinyl ether is not isolated as they react an alcohol with butyl vinyl ether in the presence of Hg(OAc)2 to spontaneously undergo the Claisen rearrangement.

claisen

JOC paper

Posted in Cascade Reactions, Claisen rearrangement, Diastereoselective, Methodology, Named Reactions, Pericyclic reactions, Sigmatropic Rearrangements | Leave a Comment »

Diastereoselective Spirocyclization

Posted by naturalproductman on June 25, 2010

Scott Rychnovsky and co-workers have published in JACS on a spirocyclization process that yields the 5,6-spirocyclic ring system of lepadiformine.

lepadiformine

JACS paper

Posted in Alkaloids, Cascade Reactions, Diastereoselective, Methodology, Ring forming, Spirocyclic centers | Leave a Comment »

Synthesis of Cyclobutanones

Posted by naturalproductman on June 16, 2010

Jun-ichi Matsuo and co-workers at Kanazawa University have published in Tetrahedron Letters on a chemical transformation of enol ethers and acid chlorides into cyclobutanones.

cyclobutanone

TL paper

Posted in Cascade Reactions, Cycloaddition, Diastereoselective, Methodology, Pericyclic reactions | Leave a Comment »

PIDA-Induced Cyclization

Posted by naturalproductman on June 2, 2010

Yasuyaki Kita and co-workers at Ritsumeikan University have published in Chem Comm on a PIDA induced cyclization to form spiro cyclohexadienone lactones.

PIDA

Chem Comm paper

Posted in Cascade Reactions, Diastereoselective, Hypervalent Iodine, Methodology, Ring forming, Spirocyclic centers | Leave a Comment »