One-pot conversion of alkenes

The perruthenate oxidation of alcohols has been incorporated into a one-pot conversion of alkenes into carbonyl compounds via their initial hydroboration [44], Overall yields can be as high as 98%. Where the initial alkene also contains carbonyl groups these are reduced in the first step and are reoxidized by the perruthenate. 

Regio- and enantioselective Heck reactions of 2 3-dihydrofuran with aryl and alkenyl triflates in the presence of the chiral ligand (R)-BITIANP provides 2-substituted 23-dihydro-furans with complete regioselectivity, high enantioselectivity (86-96% ee) and good yields (76-93%) <99CC1811>. A catalytic oxyselenylation-deselenylation reaction of alkenes offers a stereoselective one-pot conversion of alkenes into 2 -dihydrofurans <99EF0797>. 

A one-pot conversion of alkenes to iV-methylaziridines has been achieved by aminopalladation followed by an oxidative woik-up with bromine (Scheme 15). The reaction is stereospecific, as shown by deuteration experiments, but has been little exploited. - 2-Aminopalladium compounds such as (21) are extremely versatile depending on starting compounds and work-up reagents, Aey can be made to yield a wide variety of products (Scheme 16). ... 

An interesting development reported by John Brown is the conversion of the intermediate boronate into a primary amine. This provides a route for the one-pot conversion of alkenes into enantiomerically enriched amines. Whilst the intermediate boronates cannot be directly converted into amines, treatment of the boronates with a Grignard reagent forms a borane, which is then converted into an amine using standard procedures. For example, the alkene (2.172) is converted into the amine (2.173) in a one-pot process. As catecholborane (2.171) is air-sensitive and somewhat unstable under these reaction conditions, some work has been directed towards the use of other more stable boranes, most notably... 

One pot conversion of alkenes into the corresponding trans-acetoxy alcohols was realized using Zr(Oi-Pr)4 catalyst with bis(trimethylsilyl) peroxide and trimethylsilyl acetate (Equation 44) [1, 50c]. The reaction is applicable for a series of cyclic alkenes to afford the corresponding 1,2-trans-acetoxy alcohols in high yields. NMR observation of the reaction mixture revealed the intermediacy of the corresponding... 

Hie highest with substrates containing two such groups. The reaction of configuration at the oxidized carbon atom, used for a one-pot conversion of a terminal alkene into the anti-ty a hydrosilylation-oxidation sequence (equation II). ... 

A one-pot conversion of vic-diols to alkenes can be achieved at room temperature using TMS-I generated in situ (equation 16). °... 

A simple one-pot conversion of phenols to arenes by the reaction of fluoroalkanesul-fonyl fluoride with phenols, i.e. without isolating aryl fluoroalkanesulfonates, in the presence of alkenes, alkynes or triethylammonium formate, can be accomplished in good yields139 (equation 119). 

Meyers extension and Chan s modification represent one-pot conversions of sulfones into alkenes. These are almost invariably used in modern synthetic applications due to the in )roved convenience and synthetic efficiency conpared to the classic (two-step) RBR. The Chan method is recommended as the first choice when contemplating the use of the RBR in synthesis. This is due to the highly dispersed nature of the solid-supported base, which provides more reliable reactivity. 

The aminomercuration-demercuration reaction has provided two examples for primary to secondary amine conversion.In one, Markovnikov addition of the aminomercurial (10) to an alkene, followed by ligand exchange with sodium hydroxide and subsequent reduction with sodium borohydride, yields the secondary amine (11) in a one-pot reaction (Scheme 10). In the other,vicinal diamines (12) are the products from the one-pot reaction of alkenes with tetrafluoroboric acid and mercury(ll) oxide in the presence of excess primary amine (Scheme 11). Both reactions work equally well with secondary amines. 

Oxirans. - The synthesis of l,2-anhydro-3,4-di-0-benzyl-6-deoxy-a-D-glucopyranose and its conformational analysis have been reported. A range of epoxides have been prepared by base treatment of bromohydrins, which were made by reaction of hydrogen bromide with aldonolactones. A one-pot conversion of vicinal diols into epoxides employs halohydrin ester intermediates generated from cyclic orthoacetates and either acetyl bromide or trimethylsilyl chloride. Levoglucosenone has been transformed into l,6 3,4-dianhydro-p-D-talopyranose by way of a trn/w-iodo-acetoxylation of the alkene moiety... 

A one-pot, high yielding procedure involving nucleophilic displacement with iodide followed by elimination of hydrogen iodide using DBU in DMSO has been used to prepare 6-deoxyhex-5-enopyranoside derivatives from corresponding 6-bromo-compounds or 6-tosylates.The conversion of alkenes of this type into 2-deoxyinososes, previously known to occur in the presence of mercury(II) salts in aqueous media, has now been shown also to take place under the Influence of palladium salts and dilute acid. = ... 

When asymmetric epoxidation of a diene is not feasible, an indirect route based on asymmetric dihydroxylation can be employed. The alkene is converted into the corresponding syn-diol with high enantioselectivity, and the diol is subsequently transformed into the corresponding trans-epoxide in a high-yielding one-pot procedure (Scheme 9.5) [20]. No cpirricrizalion occurs, and the procedure has successfully been applied to natural product syntheses when direct epoxidation strategies have failed [21]. Alternative methods for conversion of vicinal diols into epoxides have also been reported [22, 23]. 

The three-reaction one-pot procedure allows the conversion of suitable alcohols to cyclic alkenes in relatively good yields, one example is given in Scheme 17. 

The ene-yne CM of fatty acid-derived terminal alkenes with several alkyne derivatives was shown by Bruneau et al. [75], These reactions, which led to renewable conjugated dienes, were performed in a one-pot two-step procedure. In the first step, the ethenolysis of methyl oleate was performed in the presence of the first-generation Hoveyda-Grubbs catalyst (2.5 mol%) using dimethyl carbonate as solvent at room temperature. After completion of the ethenolysis (90% conversion), C4 (1 mol%) and the corresponding alkyne (0.5 equivalents with respect to olefins) were added and the reaction was run at 40°C for 2 h (Scheme 9). The desired dienes were thus obtained in high yields close to the maximum theoretical value (50%). Moreover, in order to maximize the formation of functional dienes, the same reaction sequence was applied to the diester obtained by SM of methyl oleate. In this way, the yield of functional dienes was increased up to 90% depending on the... 

It was noticed by Rickborn and Wood [4] and Field and Galagher [5] that cyclic tetrasubstituted alkenes undergo such a isomerization under much milder conditions. This approach enables highly stereoselective conversion of a variety of cyclic tetrasubstituted alkenes of type 34 into polyfunctional products of type 37 in one-pot reactions via the intermediate organoboranes 35 and 36 (Scheme 5) [6-8]. 

Sequential one-pot RCM-cyclisation of dienes and alkene isomerisation have been achieved through conversion of the Ru-alkylidene RCM catalyst into a Ru-hydride catalyst, providing an efficient route to 3,4-dihydro-27/-pyrans from acyclic dienes <02JA13390>. 

Cocyclotrimerization, if applied to 1,5-hexadiynes 7, leads to benzocyclobutenes 8. After smooth thermal ring opening, these give highly reactive ort/io-quinodimethanes 9, which can be trapped by Diels-Alder reaction with an alkene or hetero-carbon multiple bond. If these dienophiles are in a side chain of the primary diync, the conversion leads in a one-pot version to carbo- and heterocyclic polycyclic systems with defined trans stereochemistry at the newly... 

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