- Chemoselective rearrangement reactions of sulfur ylide derived from diazoquinones and allyl/propargyl sulfides
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Here, we describe three types of rearrangement reactions of sulfur ylide derived from diazoquinones and allyl/ propargyl sulfides. With Rh2(esp)2 as the catalyst, diazoquinones react with allyl/propargyl sulfides to form a sulfur ylide, which undergoes a chemoselective tautomerization/[2,3]-sigmatropic rearrangement reaction, a Doyle?Kirmse rearrangement/Cope rearrangement cascade reaction, or a Doyle?Kirmse rearrangement/elimination reaction, depending on the substituent of the sulfides. The protocol provides alkenyl and allenyl sulfides and multisubstituted phenols with moderate and high yields.
- Zhou, Cong-Ying,Yan, Sijia,Rao, Junxin
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supporting information
p. 9091 - 9096
(2020/12/02)
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- Fast ruthenium-catalysed allylation of thiols by using allyl alcohols as substrates
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The allylation of aromatic and aliphatic thiols, by using allyl alcohols as substrates, requires only minutes at ambient temperature with either a Ru Iv catalyst, [Ru(Cp*)(n3CH5)(CH 3CN)2](PF6)2 (2; Cp* = pentamethylcyclopentadienyl) or a combination of [Ru(Cp*)(CH 3CN)3](PF6) and camphor sulfonic acid. Quantitative conversion is normal and the catalyst possesses high functional-group tolerance. The use of [Ru(Cp*)(CH3CN) 3](PF6) alone affords poor results. A comparison is made to the results from catalytic runs based on the use of carbonates rather than alcohols, by using 2 as the catalyst, and it is shown that the products from the alcohols are formed faster, so there is no advantage in using a carbonate substrate. The observed branched-to-linear (b/1) ratios when using substituted alcohols decrease with time suggesting that the catalysts isomerise the products. A new methodology from which one can select the desired isomeric product is proposed. DFT calculations and NMR spectroscopic measurements, by using an arene sulfonic acid as co-catalyst, suggest that 6-complexes are not relevant for the catalytic system. Moreover, the DFT results indicate that l)any rf-complexes from the acids RC6H4SO 3H result from deprotonation of the acid, 2) complexation of the thiol, via the deprotonated sulfur atom, is preferred over complexation of the O atom of the sulfonate, RC6H4SO3and 3) a sulfonate O-atom complex will be difficult to detect.
- Zaitsev, Alexey B.,Caldwell, Helen F.,Pregosin, Paul S.,Veiros, Luis F.
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scheme or table
p. 6468 - 6477
(2010/02/28)
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- Enantiocontrolled construction of bicyclic proline derivatives via one-pot generation and intramolecular trapping of chiral stabilised azomethine ylids
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Aldehydes possessing unsaturation at C-5 or C-6 condense with nylmorpholin-2-one (1), generating chiral stabilised azomethine ylids which undergo concommitant diastereospecific intramolecular 3+2 dipolar cycloaddition to furnish adducts (2), (4), and (5)
- Harwood,Lilley
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p. 537 - 540
(2007/10/02)
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- (ALLYLTHIO)ACETATE DIANION AS A MEW AND CONVENIENT REAGENT FOR THE STEREOSELECTIVE SYNTHESIS OF (2E,4E)DIENOATES FROM ALKYL HALIDES
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Treatment of (allylthio)acetate with lithium diisopropylamide followed by the addition of s-butyllithium produced a new dianion which could react with a variety of alkyl halides exclusively at the allylic position.The high regioselectivity of the allylic alkylation could be realized in the case of methyl (allylthio)acetate dianion.A convenient and general method for the stereoselective synthesis of (2E,4E)dienoates from alkyl halides has been developed.
- Tanaka, Kazuhiko,Terauchi, Makoto,Kaji, Aritsune
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p. 315 - 318
(2007/10/02)
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