Stereoselective total synthesis of (+)-polyrhacitide A

A facile stereoselective total synthesis of secondary metabolite (+)-polyrhacitide A is described. Stereoselective aldol reaction, Horner-Wardsworth-Emmons reaction, Evans acetal intramolecular oxa-Michael reaction and diastereoselective syn reduction reaction are the key steps involved in the target synthesis

Formal total synthesis of cyanolide A

Formal total synthesis of cyanolide A, aglycosidic dimeric macrolide is accomplished. The key reactions involved are asymmetric acetate aldol reaction, CBS reduction, and Shiina's lactonization

NbCl<SUB>5</SUB> mediated deprotection of methoxy methyl ether

An efficient cleavage of methoxy methyl ether using NbCl5 is described. This protocol works efficiently with MOM ethers of alkyl, allyl, propargyl, benzyl alcohol and phenol derivatives. MOM esters are also found to be effectively cleaved under the present conditions

Brϕnsted acid catalyzed one-pot condensation of <img src='/image/spc_char/beta.gif' border=0>-naphthol, aldehyde and active methylene substrate: Synthesis of naphthopyrans

1755-1761<span style="font-size:12.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-gb;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-GB">An efficient one-pot condensation of -naphthol, aldehyde and active methylene substrate is achieved using catalytic amount of phosphomolybdic acid. This multi-component reaction resulted in the synthesis of several naphthopyran derivatives in good yields.</span

Synthesis and Determination of Absolute Configuration of α‑Pyrones Isolated from <i>Penicillium corylophilum</i>

The first total synthesis of (<i>S</i>)-6-(2,9-dihydroxy­nonyl)-4-hydroxy-3-methyl-2<i>H</i>-pyran-2-one, 4-hydroxy-3-methyl-6-((2<i>S</i>,4<i>R</i>)-2,4,11-trihydroxy­undecyl)-2<i>H</i>-pyran-2-one, and its unnatural 2<i>R</i>,4<i>R</i>-isomer starting from commercially available 1,8-octanediol is described. The synthesis led to the revision of the proposed structural assignment of the natural product as (<i>R</i>)-6-(2,9-dihydroxy­nonyl)-4-hydroxy-3-methyl-2<i>H</i>-pyran-2-one. The key steps include chiral auxiliary mediated asymmetric acetate aldol reaction, dianion addition, and base mediated cyclization to form an α-pyrone ring