Nitrocyclopropanes synthesis

Spurred by these observations, we examined a relevant application of the method for nitrocyclopropane synthesis from nitroalkenes and dimethylsulfoxonium methylide (17), Equation 3. It had previously been employed for the synthesis of a 2,3-dideoxv-2,3-C-methylene-3-nitro-hexopyranoside, the first one of the small number of carhohvdrates containing the nitrocyclopropane structure thus far known (18). 

In all the above examples, the synthesis of nitronates (5) is rather chemose-lective. In any case, data on the formation of their structural isomers, viz, the corresponding nitrocyclopropanes (13), are lacking. However, the synthesis of five-membered nitronates (5) with the use of sulfur or selenium ylides is not chemoselective (see Scheme 3.16). 

Unfortunately, only two attempts were made to use this approach in the synthesis of five-membered cyclic nitronates (5), and only one of them could be considered as successful. In the latter case, isomeric nitrocyclopropane was obtained as the major product. Only a-functionalized nitro alcohols are readily involved in the Mitsunobu cyclization. However, the possibility of isomerization of by-products, nitrocyclopropanes, which was mentioned in the discussion of Scheme 3.16, caused the revision of this process as a procedure for the synthesis of five-membered cyclic nitronates. (A new approach to the synthesis of initial y-nitro alcohols from readily available AN was documented in Reference 64)... 

In addition to conventional generation of carbenes from nitrodiazo compounds (22) (79), target intermediates C can be prepared by oxidation of functionalized AN CH2XNO2 with phenyliodonium diacetate. The reactions of Rhodium intermediates with certain olefins afford the corresponding cyclopropanes (23). The cycloaddition reaction was performed in the presence of a catalyst. (The successful synthesis of nitrocyclopropanes from trinitromethane derivatives and nitroacetic ester was also documented (81)). 

Therefore, all prerequisites are present for the development of a general strategy for the synthesis of nitronates (24) from a-functionalized primary AN through stabilized carbenium intermediates and nitrocyclopropanes (23). This approach allows the stereoselective synthesis of nitronates (24) from simple molecules (Scheme 3.29). 

Ballini, R., Fiorini, D., and Pahnieri, A. 2007a. Synthesis and use of nitrocyclopropane derivatives, Arkivoc, 7 172-94. 

McCooey, S.H., McCabe, T. and Connon, S.J. (2006) Stereoselective synthesis of highly functionalized nitrocyclopropanes via organocatal)4ic conjugate addition to nitroalkenes. The Journal of Organic Chemistry, 71, 7494-7497. 

In 2006, a practical route for the efficient synthesis of (S)-pyrrolidin-2-yl-IH-tetrazole 5a was developed. Ley and coworkers prepared ent-SsL to catalyse the nitrocyclopropanation of cyclohexenone in the presence of... 

Kamimura, A., Kadowaki, A., Yoshida, T., Takeuchi, R., Uno, H. (2009). Stereoselective synthesis of bicychc nitrocyclopropanes by a radical-anion domino reaction. Chemistry - A European Journal, 15, 10330-10334. 

Kumaran G, Kulkami GH. Effect of the a-alkyl substituent of conjugated nitroolefins on the formation of cyclic nitronic esters vs. nitrocyclopropanes in their reaction with sulfur ylides. Synthesis 1995 1545-1548. 

---