Abstract:The use of dimethyl sulfoxide as an oxidizing agent began with the discoveries by Kornblum and co‐workers that certain α‐bromo ketones were converted into glyoxals under mild conditions by treatment with dimethyl sulfoxide, and that primary tosylates such as
n
‐octyl tosylate were converted into the corresponding aldehydes using dimethyl sulfoxide and sodium bicarbonate at 150° for 3 minutes. The initial step of the reactions involves a displacement by dimethyl sulfoxide giving an alkox… Show more
“…Traditional methods employed stoichiometric quantities of either inorganic oxidants (such as chromate) [1,2] or organic oxidants (such as activated DMSO). [3] The use of such reagents leads to environmental and economic problems associated with recycling or disposal of the reduction by-products.…”
The use of platinum group metal (PGM) catalysts for the selective oxidation of various primary and secondary alcohols under mild conditions is described. High throughput screening (HTS) techniques have been used to identify trends in catalyst activity and product selectivity. Using air as oxidant and water as solvent 5% Pt, 1% Bi/C has been identified as an efficient catalyst for the transformation of 2-octanol to 2-octanone and 1-octanol to octanoic acid. To improve aldehyde selectivity the promotion of Pt/Al 2 O 3 and Ru/C catalysts has been investigated. The use of H 2 O 2 as oxidant has been demonstrated as a suitable alternative to air.
“…Traditional methods employed stoichiometric quantities of either inorganic oxidants (such as chromate) [1,2] or organic oxidants (such as activated DMSO). [3] The use of such reagents leads to environmental and economic problems associated with recycling or disposal of the reduction by-products.…”
The use of platinum group metal (PGM) catalysts for the selective oxidation of various primary and secondary alcohols under mild conditions is described. High throughput screening (HTS) techniques have been used to identify trends in catalyst activity and product selectivity. Using air as oxidant and water as solvent 5% Pt, 1% Bi/C has been identified as an efficient catalyst for the transformation of 2-octanol to 2-octanone and 1-octanol to octanoic acid. To improve aldehyde selectivity the promotion of Pt/Al 2 O 3 and Ru/C catalysts has been investigated. The use of H 2 O 2 as oxidant has been demonstrated as a suitable alternative to air.
“…Traditional methods
(i.e., Swern oxidation, 3 Dess-Martin periodinane, 4 IBX, 5 or MnO 2 ) either provided inadequate yields of the desired product or failed completely. DDQ, 6 however, provided the desired product in 95% yield in less than 10 min.…”
A practical, chemoselective oxidation of alcohols employing catalytic quantities of DDQ as the oxidant and Mn(OAc)3 as the co-oxidant is described. Electron–rich benzylic alcohols are oxidized efficiently to their corresponding carbonyls, but less electron–rich benzylic alcohols remain unchanged. Allylic alcohols are rapidly oxidized to their corresponding aldehyde or ketone counterparts in high yields. This protocol is operationally simple, employs an inexpensive source of Mn(OAc)3, has short reaction times, and exhibits a significant chemoselectivity favoring allylic alcohols over benzylic alcohols. This procedure also avoids the use of the very large excesses of reagents and sometimes poor reproducibility that characterize previously developed reagents such as MnO2.
“…7 Reaction of epoxide 5 with excess magnesium 4-methoxyphenyl cuprate followed by standard Swern oxidation 8 furnished the (R)-ketone 7 in essentially quantitative yield. Reduction of 7 with NaBH 4 generated an inseparable mixture of syn/anti 6 in quantitative yield with 9∶1 diastereoselectivity as revealed by 1 H NMR.…”
The facile enantioselective synthesis of the di-O-methyl ethers of (-)-agatharesinol (1b), (-)-sugiresionl (2b), (+)-nyasol (3b) and (+)-tetrahydronyasol (4) were achieved in high yield. The absolute configuration of (+)-3a was confirmed via first total synthesis of (+)-3b and (+)-4.
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