Conversion of alkanes to organoseleniums and organotelluriums
The invention provides processes and materials for the efficient and costeffective functionalization of alkanes and heteroalkanes, comprising contacting the alkane or heteroalkane and a soft oxidizing electrophile comprising Se(VI) or Te(VI), in an acidic medium, optionally further comprising an aprotic medium, which can be carried out at a temperature of less than 300 C. Isolation of the alkylselenium or alkyltellurium intermediate allows the subsequent conversion to products not necessarily compatible with the initial reaction conditions, such as amines, stannanes, organosulfur compounds, acyls, halocarbons, and olefins.
1. A process for the conversion of an alkane or a heteroalkane, wherein the alkane or heteroalkane comprises at least one sp 3 -hybridized carbon atom, to a corresponding alkylselenium or alkyltellurium compound comprising
(a) contacting the alkane or heteroalkane and a soft oxidizing electrophile comprising Se(VI) or Te(VI), in an acidic medium, optionally further comprising an aprotic medium; to form the corresponding alkylselenium or alkyltellurium compound and optionally
(b) separating the respective alkylselenium or alkyltellurium compound.
2. The process of claim 1 , further comprising a step of regeneration of the soft oxidizing electrophile by contacting a Se- or Te-containing electrophile reduction product of the soft oxidizing electrophile and the alkane or heteroalkane with an oxidant under conditions suitable to regenerate the soft oxidizing electrophile comprising Se(VI) or Te(VI).
3. The process of claim 1 , wherein the alkane is methane, ethane, or propane, or any mixture thereof.
4. The process of claim 1 , wherein the acidic medium is free of a superacid.
5. The process of claim 2 , wherein the regenerating oxidant comprises any of molecular oxygen, hydrogen peroxide, chlorine, nitric acid, or ozone.
6. The process of claim 2 , wherein the regenerating oxidant consists essentially of hydrogen peroxide.
7. The process of claim 1 , wherein the acidic medium consists essentially of trifluoroacetic acid, acetic acid, or a mixture thereof.
8. The process of claim 1 , wherein the acidic medium further comprises an aprotic medium, comprising an anhydrous, poorly nucleophilic, polar liquid.
9. The process of claim 8 , wherein the aprotic medium is liquid sulfur dioxide, trifluoroethanol, tetrachloroethane, or dichloromethane, or a mixture thereof.
10. The process of claim 1 , wherein (i) the soft oxidizing electrophile comprising Se(VI) or Te(VI) (ii) the electrophile reduction product thereof, or (iii) both, are immobilized on a solid support contained within a reactor.
11. The process of claim 1 , wherein the alkane or the heteroalkane and the soft oxidizing electrophile comprising Se(VI) or Te(VI) in an acidic medium are contacted in a reactor for a first period of time, followed by a second period of time in which the electrophile reduction product is contacted with an oxidant to regenerate the soft oxidizing electrophile.
12. The process of claim 1 , wherein the process is carried out in a two reactor circulating liquid phase system, wherein the reaction of the alkane or the heteroalkane and the soft oxidizing electrophile is carried out in a first reactor, and the step of oxidatively regenerating the separated electrophile reduction product to the soft oxidizing electrophile is carried out in a second reactor.
13. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a hydrazine, a hydroxylamine, or an amine, to provide an amine corresponding to the alkane or heteroalkane.
14. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a stannous salt in the presence of an oxidant to provide an organotin compound corresponding to the alkane or heteroalkane.
15. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a sulfur-containing reagent, to provide a thiolated alkane or heteroalkane.
16. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and formaldehyde and an amine, in the presence of an oxidant, to yield a homologated derivative of the starting alkane or heteroalkane with a carboxamido group.
17. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a phosphine to provide a phosphinylated alkane or heteroalkane corresponding to the starting material.
18. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a very weak base, such as acetate or trifluoroacetate, to provide an alkene.
19. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and carbon monoxide, to provide an acyl compound.
20. The process of claim 1 further comprising a step of contacting the alkylselenium or alkyltellurium compound and a halide in the presence of an oxidant to provide a halocarbon derivative of the starting alkane or heteroalkane substrate.
21. The process of claim 1 , wherein the alkylselenium or alkyltellurium compound is separated.