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Reaction of (trialkylstannyl) copper reagents with acetylenic compounds

University of British Columbia

The reaction of a number of (trialkylstannyl)copper reagents with 2-alkynoates, N,N-dimethyl-2-alkynaraides and 1-alkynes is described. It has been found that the (trimethylstannyl)copper reagents 14 and 43-46 efficiently transfer the trimethylstannyl group to oc-alkynoates. Reagent 14 (THF, -48°C) provided predominantly the (Z)-3-trimethyl-stannyl-2-alkenoate (22), reagents 44 and 45 (THF, -48°C) afforded essentially exclusively the corresponding (E) isomer 21, while reagents 43 and 46 gave a mixture of isomers. Using the above methodology, ethyl 2-pentynoate was converted into either (Z)- or (E)-3-( tri-n-butylstannyl)-2-pentenoate. The (E) isomer was converted into the vinylstannane 188 which was transformed (MeLi, THF, -20°C) into the corresponding stereochemically homogeneous vinyllithium reagent and elaborated into the acyl portion of (±)-triophamine (172), a diacylguanidine recently isolated from Triopha catalinae. Reaction of 2-alkynoates with excess 44 or 45 (THF, 0°C) afforded, as essentially the only products, (E)-2,3-bis(trimethyl-stannyl)-2-alkenoates (115). One member of this new class of compounds, ester 114 (=115, R = Me, R' = Et) was selectively transmetalated (MeLi, THF, -98°C) and the resultant nucleophilic species was allowed to react with a number of reactive electrophiles to produce esters of general structure 141.

Text

2010-05-02

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http://hdl.handle.net/2429/24280

Chemistry

University of British Columbia

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