Preparation of benzene, furan, and thiophene analogs of duocarmycin SA employing a newly-devised phenol-forming reaction.
Five A-ring analogs of duocarmycin SA 9a-e were synthesized in racemic form modifying our second synthetic route toward duocarmycin SA. The problem encountered at the crucial phenol forming step to secure 17a, b from 16a, b under the conventionally used Kuwajima conditions was overcome by devising a more convenient method: simple heating of 16a-c in benzene in the presence of bis(triphenylphosphine)palladium(II) chloride (10 mol%), cesium carbonate (3 eq), and triphenylphosphine (0.3 eq) gave 17a-c in high yields of 86-91%. The intermediates 17a-e were readily led to the A-ring analogs (+/-)-9a-e almost according to the reported route.
Muratake
H
H
Research Foundation Itsuu Laboratory, Tokyo, Japan.
Hayakawa
A
A
Natsume
M
M
D001554:Benzene / Q000737:chemistry*; D000080890:Duocarmycins; D005663:Furans / Q000737:chemistry*; D007211:Indoles; D015394:Molecular Structure; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013057:Spectrum Analysis; D013876:Thiophenes / Q000737:chemistry*
D000080890:Duocarmycins; D005663:Furans; D007211:Indoles; D011758:Pyrroles; D013876:Thiophenes; C066098:duocarmycin SA; D001554:Benzene