Nitroalkanes in C–C bond forming reactions: a crystal structure of a complex of a guanidine catalyst and a nitroalkane substrate

Abstract

1,5,.0]dec-5-ene (TBD), a good catalyst for nitroalkanes in C-C bond forming reactions, forms a 1 : 1 complex 3 with a-nitrotoluene as a substrate, as shown by a crystal structure determination.

Guanidines in Organic Synthesis

“…(Table 4.3) A ketonic 3-phenyl-2-butanone can work as an acceptor under the above conditions, but reactivity is low (23% yield, 39% ee). (3), in many cases superior to 1, are proven to be powerful catalysts for Henry (nitro-aldol) reaction [29,39]. The X-ray structure of the TBDphenylnitromethane complex has been reported [39].…”

“…(3), in many cases superior to 1, are proven to be powerful catalysts for Henry (nitro-aldol) reaction [29,39]. The X-ray structure of the TBDphenylnitromethane complex has been reported [39]. Smooth reactions of aldehydes or ketone with nitroalkanes were observed to afford 2-nitroalkanols under mild conditions when TMG (1) was used as not only a base but also a solvent [40] ( acetophenone or acyclic ketones do not work as electrophiles because of no reaction or predominant self condensation, respectively.…”

Synthesis and Structural Characterisation of cis‐ and trans‐[(hppH)2PtCl2], [(hppH)3­PtCl]+Cl– and Some New Salts of the [hppH2]+ Cation (hppH = 1,3,4,6,7,8‐Hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine): The Importance of Hydrogen Bonding

“…- [26] and [{hppH 2 } + ] 3 -[{TaCl 6 } -] 2 [Cl] -, are already known. [27] Some of these are of interest for the study of reactions involving hppH as a catalyst, such as the Michael addition of nitroalkanes, [25] + cations that interact only very weakly with the borate counterions. The C1-N1 and C1-N2 bond lengths are 133.5 and 134.9 pm, respectively, and the C1-N3 bond is significantly shorter 132.6 pm.…”

Nitronate Anion Recognition and Modulation of Ambident Reactivity by Hydrogen-Bonding Receptors

“…Both Davis [7] and Wynberg [8] have previously explored the use of amidinium-and guanidiniumbased receptors to form complexes with nitronates by using X-ray crystallography to show the formation of discrete hydrogen bonds between the nitronate and receptor. The crucial nature of the bidentate interaction was verified in solution by the observation of proton transfer to form nitronates only when a bidentate receptor was present.…”