lecture890708 - Workspace
lecture890708 - Workspace
lecture890708 - Workspace
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Linear C 5n ‘head-to-tail’ Pyrophosphates<br />
• head-to-tail C 5 oligomers are the key precursors to isoprenoids<br />
– geranyl pyrophosphate (C 10) is formed by S N1 alkylation of DMAPP by IPP → monoterpenes<br />
– farnesyl (C 15) & geranylgeranyl (C 20) pyrophosphates are formed by further S N1 alkylations with IPP:<br />
evidence for S N1:<br />
F 3C<br />
OPP<br />
H*<br />
DMAPP<br />
H<br />
F 3C<br />
OPP<br />
S N1<br />
OPP<br />
ionisation is 1,000,000 times slower<br />
OPP<br />
OPP<br />
intimate ion pair<br />
H S H R<br />
IPP<br />
via<br />
OPP<br />
OPP inversion<br />
H R<br />
H S<br />
OPP<br />
*H<br />
OPP<br />
gerenyl pyrophosphate (C 10)<br />
farnesyl pyrophosphate (C 15)<br />
gerenylgeranyl pyrophosphate (C 20)<br />
H<br />
IPP<br />
IPP<br />
OPP<br />
OPP<br />
MONOTERPENES (C 10)<br />
SESQUITERPENES (C 15)<br />
TRITERPENES (C 30)<br />
DITERPENES (C 20)<br />
CAROTENOIDS (C 40)
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