In 2001,Lee, Chul Bom; Wu, Zhicai; Zhang, Fei; Chappell, Mark D.; Stachel, Shawn J.; Chou, Ting-Chao; Guan, Yongbiao; Danishefsky, Samuel J. published 《Insights into Long-Range Structural Effects on the Stereochemistry of Aldol Condensations: A Practical Total Synthesis of Desoxyepothilone F》.Journal of the American Chemical Society published the findings.Recommanded Product: 16982-21-1 The information in the text is summarized as follows:
A processable total synthesis of a potent antitumor agent, desoxyepothilone F [dEpoF, 21-hydroxy-12,13-desoxyepothilone B, 21-hydroxyepothilone D (I; R1 = Me, R2 = OH)], has been accomplished. The route is highly convergent. The new technol. has also been applied to a total synthesis of 12,13-desoxyepothilone B [dEpoB (I; R1 = Me, R2 = H)]. The crucial point of departure from previous syntheses of I (R1 = Me, R2 = H, OH) involves presentation of the C1-C11 sector for Suzuki coupling with C3 in reduced form. Hitherto, the required S stereochem. at C3 had been implemented via reduction of a keto function after Suzuki coupling. Whereas that chem. worked quite well in a synthesis of I (R1 = Me, R2 = H), it was not transferable to a high-yielding synthesis of I (R1 = Me, R2 = OH). The reduction of the keto group at C3 via a Noyori protocol after Suzuki coupling had proved to be very difficult. In our current approach, two consecutive aldol reactions are used to fashion the acyl sector. In the first aldol condensation, C6 becomes attached to C7. Following protection at C7, a two-carbon acetate equivalent is used to join C2 and C3 with very high asym. induction at C3. Only after this center has been implemented is the Suzuki reaction conducted. This major advance allowed us to synthesize I (R1 = Me, R2 = OH) in a straightforward fashion. These findings found ready application in the total synthesis of dEpoB. Another part of the study involved anal. of the factors associated with aldol condensations joining C6 to C7. In the work described herein, the consequences of the status of C3 in promoting the C6-C7 aldol coupling are probed in detail. Dramatic stereochem. long-range effects uncovered during the study are described, and a working model to explain these effects has emerged. In the experimental materials used by the author, we found Ethyl 2-amino-2-thioxoacetate(cas: 16982-21-1Recommanded Product: 16982-21-1)
Ethyl 2-amino-2-thioxoacetate(cas: 16982-21-1) belongs to anime. Reaction with nitrous acid (HNO2), which functions as an acylating agent that is a source of the nitrosyl group (―NO), converts aliphatic primary amines to nitrogen and mixtures of alkenes and alcohols corresponding to the alkyl group in a complex process. This reaction has been used for analytical determination of primary amino groups in a procedure known as the Van Slyke method.Recommanded Product: 16982-21-1
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics