Synthesis of naphtho[2,3-b]pyrandiones: (-)-cryptosporin was written by Brade, Walter;Vasella, Andrea. And the article was included in Helvetica Chimica Acta in 1989.Category: amides-buliding-blocks This article mentions the following:
A new method for the synthesis of naphtho[2,3-b]pyrandiones from sulfonyl lactones and 1-nitroglycals is presented. Thus, 3-phenylsulfonylphthalide (I, R = H) reacted with the 1-nitroglycal II in the presence of LiN(CHMe2)2 at room temperature to give the naphthopyrandione III in high yields. Reaction at a lower temperature led to the intermediate Michael-addition products. I (R = OCH2OCH2CH2OMe) and the 1-nitroglycal IV were prepared for the synthesis of the title compound (V) by base-promoted condensation and deblocking. In the experiment, the researchers used many compounds, for example, N,N-Diethylsalicylamide (cas: 19311-91-2Category: amides-buliding-blocks).
N,N-Diethylsalicylamide (cas: 19311-91-2) belongs to amides. Amides can be viewed as a derivative of a carboxylic acid RC(=O)OH with the hydroxyl group –OH replaced by an amine group −NR′R″; or, equivalently, an acyl (alkanoyl) group RC(=O)− joined to an amine group. Amides can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent.Category: amides-buliding-blocks
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics