Catalytic Cyclotrimerization Pathway for Synthesis of Selaginpulvilins C and D: Scope and Limitations

Abstract

A facile and unified approach to the main selaginpulvilin's framework was achieved by catalytic [2 + 2 + 2]cyclotrimerization of a triyne with monosubtituted alkynes. The reaction proceeded with high "ortho" selectivity by using Wilkinson's catalyst (RhCl(PPh 3 ) 3 ) under ambient conditions with reasonable yields. The scope of the reaction with respect to the alkyne as well as the catalytic system was evaluated. The formal total modular syntheses of selaginpulvilin C and D were accomplished by transformation of the cyclotrimerization's products.

Recent advances in the cascade reactions of enynols/diynols for the synthesis of carbo- and heterocycles

“…Subsequently, the same group used a similar approach to prepare fluorenols from terminal alkynes and diynols bearing terminal propargylic alcohols under Cp*Ru(cod)Cl or RhCl(Ph 3 P) 3 catalysis. 69 A series of disubstituted fluorenols were obtained in moderate yields. Compared to the use of internal alkynes as reactants for this [2 + 2 + 2]-cyclotrimerization, using terminal alkynes as substrates resulted in lower efficiency and moderate selectivity.…”

Recent Progress in Metal-Catalyzed [2+2+2] Cycloaddition Reactions

“…The reaction was performed with a triyne in the presence of 10 mol% RhCl(PPh 3 ) 3 in DCE at 90 °C in 12-64% yield (Scheme 39). 101 The scope of the cycloaddition of triynes with diversely functionalized internal alkynes was examined. The cycloaddition proceeded with a high ortho regioselectivity up to 13.1:1 in reasonable yields.…”

Synthesis and Structure Confirmation of Selagibenzophenone C

“…With regards to the synthetic achievements, several approaches were developed towards selaginpulvilines [14–19] and selaginellins [20,21] . Previously we have reported the synthesis and the clarification of the ambiguity related to the position of substitution of the benzophenone core of selagibenzophenone A and B [22] .…”

“…[2] These compounds have shown various biological activities, including antimicrobial, [9] cytotoxic, [10] antidiabetic, [11] anti-cancer [12] and phosphodiesterase-4 (PDE4) inhibitory properties. [2,13] With regards to the synthetic achievements, several approaches were developed towards selaginpulvilines [14][15][16][17][18][19] and selaginellins. [20,21] Previously we have reported the synthesis and the clarification of the ambiguity related to the position of substitution of the benzophenone core of selagibenzophenone A and B.…”