ChemInform Abstract: Conversion of Nitriles into Aldehydes by Diisobutylaluminum Hydride‐ Dimethyl Sulfide Complex.

Abstract

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Largazole Analogues Embodying Radical Changes in the Depsipeptide Ring: Development of a More Selective and Highly Potent Analogue

“…Attempts to isomerize this mixture to the desired E isomer in high yields under acidic and basic conditions were not successful. Therefore, the nitrile mixture was taken to the next step and reduced with DIBAL-H to an E / Z mixture ( E : Z , 5:1) of the corresponding aldehydes . Gratifyingly, the slow passage of the mixture through a silica column ensured complete isomerization to the desired E -isomer and the aldehyde 33 was obtained in 85% overall yield without the need for tedious separation procedures.…”

“…To a solution of triphenylmethanethiol (1.38 g, 5 mmol, 1 equiv) in dichloromethane (20 mL) were added acrolein (0.393 g, 7 mmol, 1.4 equiv) and triethylamine (0.71 g, 7 mmol, 1.4 equiv). The reaction mixture was stirred for 1 h at room temperature and was concentrated under reduced pressure to give aldehyde 36 as an off-white solid (1.66 g, 99% (38). To a suspension of (cyanomtheyl)triphenylphosphonium chloride (5.06 g, 15 mmol, 1.5 equiv) in dry dichloromethane (50 mL) was added triethylamine (3.80 g, 38 mmol, 3.9 equiv).…”

“…Therefore, the nitrile mixture was taken to the next step and reduced with DIBAL-H to an E / Z mixture ( E:Z , 5:1) of the corresponding aldehydes. 38 Gratifyingly, the slow passage of the mixture through a silica column ensured complete isomerization to the desired E -isomer and the aldehyde 33 was obtained in 85% overall yield without the need for tedious separation procedures. Diastereoselective aldol reaction of the aldehyde 33 with acetyl Nagao auxiliary 32 gave alcohol 30 , the S -stereochemistry of the new chiral center of which was confirmed by Mosher ester analysis.…”