合成这些 de [dimethyl-5,5 dioxannylidene-2]-3 cyclopentanecarboxylate demethyle a partir dedimethyl-6,6 methylene-1 dioxa-4,8 spiro [2.5] 辛烷和 de crotonate demethyle。Le crotonate demethyle peut etre 替换 par d'autres 酯(例如庚烯-2oate demethyle)或内酯(例如二氢呋喃酮-2)。在 obtient dans ce dernier cas des 上推导 de cyclopenta [c] furannone
Thermal Hetero [3 + 2] Cycloaddition of Dipolar Trimethylenemethane to O-Alkyloximes. Straightforward Synthetic Routes to Substituted Pyrrolidines and Prolines
摘要:
Thermal hetero [3 + 2] cycloaddition reaction of a dipolar trimethylenemethane 2 with an O-alkyloxime produces a substituted pyrrolidine. Thus, heating of a mixture of an alkylidenecyclopropane 1 an anti-O-alkyloxime 3 proceeds smoothly in good yield to give a substituted pyrrolidine 4 bearing a ketene acetal group in its 3-position, which upon hydrolysis under mild conditions gives a 3-alkoxycarbonylpyrrolidne 5 in quantitative yield. On the other hand, the cycloaddition to a syn-oxime is extremely slow. The cycloaddition reaction can be achieved by starting with nearly equimolar quantities of the two starting materials, and the reaction is quite insensitive to the choice of solvent and to the presence of oxygen and water. In the reaction of a substituted methylenecyclopropane 1 (R not equal H), the reaction may take place with high regio-and stereoselectivity, which is in consonance with the concerted nature of the cycloaddition reaction. The present synthesis represents one of the rare examples of the imine-based route to pyrrolidines, which have been much less explored than the 1,3-dipolar cycloaddition route using olefin and azomethine ylide.
General synthesis of cyclopropenones and their acetals
作者:Masahiko Isaka、Satoshi Ejiri、Eiichi Nakamura
DOI:10.1016/s0040-4020(01)88873-6
日期:——
Metalated cyclopropenone acetals 5 react with a variety of electrophiles, including alkyl halides, carbonylcompounds, vinyl iodides, vinyl triflates, and aryl iodides, to give substituted cyclopropenone acetals in high yield. Hydrolysis of the acetal under acidic conditions gives the corresponding cyclopropenone. The reaction sequence has realized an efficient synthesis of an antibiotic penitricin
Hydrostannation of Cyclopropene. Strain-Driven Radical Addition Reaction
作者:Shigeru Yamago、Satoshi Ejiri、Eiichi Nakamura
DOI:10.1246/cl.1994.1889
日期:1994.10
cyclopropenone acetals with trialkyltinhydride takes place smoothly under radical conditions to afford a variety of 2-alkyl-3-stannylcyclopropanone acetals in high yield. Comparison of the cyclopropene with acetylenes with the aid of inter- and intramolecular competitive experiments revealed the kinetically controlled nature of the reaction of the cyclopropene reaction.
A variety of substituted cyclopropenone ketals have been prepared by electrophilic trapping (protonolysis and alkylation) of sodium salts of cyclopropenone ketals that have been generated directly from the ketals of 1,3-dichloroacetone derivatives through cyclization with NaNH2 in a liq. NH3/ether mixture.
Cyclopropenone-containing cysteine proteinase inhibitors. Synthesis and enzyme inhibitory activities
作者:R Ando
DOI:10.1016/s0968-0896(99)00007-3
日期:1999.4
acetal derivatives (2, R2 = metal) with N-protected alpha-aminoaldehydes 4 to obtain the adduct 5, and succeeded in the preparation of highly potentiated cysteine proteinase inhibitors 8 after several steps transformations. They showed strong inhibitory activities only to cysteine proteinases such as calpain, papain, cathepsinB, and cathepsin L and not to serine (e.g. thrombin and cathepsin G) and
Im Gegensatz zu Cyclopropen, 3,3‐Dimethoxycyclopropen oder 1,2‐Diphenylcyclopropenon reagiert unsubstituiertes Cyclopropenon mit verschieden substituierten Triazinen regioselektiv an der NN‐Bindung zu neuen Pyrazolo[1,2‐a]1,2,4‐triazin‐6‐onen in mittleren Ausbeuten. Die Struktur des Pyrazolo[1,2‐a]1,2,4‐triazins 11 konnte mittels Röntgenstrukturanalyse gesichert werden.