Synthesis of Six-Membered Compounds by Environmentally Friendly Cyclization Using Indirect Electrolysis
摘要:
[Ni(cyclam)](ClO4)(2)-catalyzed indirect electroreduction of olefinic bromides produced six-membered compounds in low to high yields. The synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner. Lactam 66, the synthetic precursor of tacamonine, was prepared in 49% yield as a mixture of two diastereoisomers. The electrolysis of the bromoacetates gave the debrominated compounds in good yields.
Silica gel promotes the lactonization and the concomitant aryl rearrangement of 4-aryl-5-tosyloxy pentanoates (3c-j) to give γ-lactones along with complete inversion in high yields.
Reaction of Methyl 4,5-Epoxy-(2E)-pentenoate with Arylcopper Reagents.
作者:Shinji NAGUMO、Shigeyuki IRIE、Hiroyuki AKITA
DOI:10.1248/cpb.44.675
日期:——
The reaction of methyl 4, 5-epoxy-(2E)-pentenoate (1) with various arylcopper reagents was studied. Basically, all arylcopper reagents react with 1 in SN2 fashion. However, addition of BF3 causes reversal of the regioselectivity, which can be rationalized in terms of a two-step conversion by way of methyl 4-bromo-5-hydroxy-2-pentenoate (5).
The reaction of methyl (E)-4,5-epoxypent-2-enoate with arylcopper: the unique role of boron trifluoride in determining regioselectivity
作者:Shinji Nagumo、Shigeyuki Irie、Hiroyuki Akita
DOI:10.1039/c39950002001
日期:——
Excess BF3 causes regioselectivity reversion in the reaction of methyl 4,5-epoxypent-2-enoate 1 with Ph2CuLi; this is rationalised by a two step conversion via methyl 4-bromo-5-hydroxypent-2-enoate 5.