Linkers germanium-based

Chemistry similar to this was used in Ellman s paper to promote application of a silicon-based traceless linker.62 The full report on this work63 shows that both aliphatic and aromatic acid chlorides may be used in the coupling step. The same,approach is also shown to be successful with a germanium-based linker in place of the silicon. The couplings were typically performed for 1 h only, with equilibration time of a few minutes... 

Germanium-based linkers for solid-phase synthesis. 1599... 

Chris Diaper received his BSc in chemistry in 1996 from the University of Bradford, UK and his PhD in 2000 from the University of Sheffield under the supervision of Dr Alan Spivey. After postdoctoral work at the University of Nottingham with Prof Gerry Pattenden he moved to his current position as a postdoctoral fellow at the University of Alberta, Canada working with Prof John Vederas. His research interests include the development of germanium based linkers for solid-phase sjmthesis, the total synthesis of marine natural products and mechanistic aspects of the diaminopimelate (DAP) biosynthetic pathway. 

There are only a few examples for germanium-based linkers in solid phase synthesis, hi general, the linker systems and the cleavage conditions are very similar to the silicon-based linkers that were introduced before. Two important germanium linkers are shown in Fig. 18. 

Sdieme 101 Germanium-based linkers for traceless release and formation of haloarenes... 

Cleavage of all the linkers described above provide a functional group (carboxylic acid, amide, amine, etc) at the anchoring position. Silyl-based handles 71,72, and 73 as well as germanium-based handle 74 insert a C-H bond at the anchoring position and are referred to as traceless (Fig. 15) [82-... 

For the attachment and the traceless release of electron-deficient aromatics, germanium-based hnkers of type 89 (Fig. 10) have been developed [103, 104]. This linker has the advantage that it is fairly stable towards strongly basic conditions and strong nucleophiles. 

Generation of a-ketoenamines (Table 8, entry 8) [456] Spivey et al. [456] performed a pyrazole synthesis with a polymer-supported acetophenone and a germanium-based traceless linker. The support-bound acetophenone was allowed to react with dimethylformamide dimethyl acetal (Bredereck s reagent) [498]. Subsequent reaction of the resulting a-ketoenamine with aryl hydrazine hydrochlorides gave the pyrazoles. 

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