69489-14-1Relevant articles and documents
Nucleophilic additions on acetyldioxanes derived from (?)-(1R)-myrtenal used as chiral auxiliaries: substituent effects on the stereochemical outcome
Becerra-Martínez, Elvia,Ayala-Mata, Francisco,Velázquez-Ponce, Pedro,Medina, Manuel E.,Jiménez-Vazquez, Hugo A.,Joseph-Nathan, Pedro,Zepeda, L. Gerardo
, p. 1350 - 1358 (2017)
The synthesis of acetyldioxanes 4 and 9a starting from (?)-(1R)-myrtenal is described. The products were treated with a representative series of nucleophilic reagents (RMgX, RLi, NaBH4 and LiAlH4) to assess the effect of the substituent at C-3 on the stereochemical outcome. It was observed that the nucleophiles preferred the re-face of the C[dbnd]O group when the equatorial substituent at C-3 was a methyl group, whereas a phenyl group at the same position induced the addition through the si-face, thus allowing access to either desired stereochemistry of a final product. This behavior suggests that the formation of the expected Cram-chelated coordination complex takes a coplanar orientation with the C-3 equatorial substituent. Moreover, Grignard reagents were the most stereoselective nucleophiles. The stereochemistry of the addition was established by X-ray diffraction and chemical correlation.
Enantioselective fluorination of α-branched aldehydes and subsequent conversion to α-hydroxyacetals via stereospecific C-F bond cleavage
Shibatomi, Kazutaka,Kitahara, Kazumasa,Okimi, Takuya,Abe, Yoshiyuki,Iwasa, Seiji
, p. 1388 - 1392 (2016/02/05)
The highly enantioselective fluorination of α-branched aldehydes was achieved using newly developed chiral primary amine catalyst 1. Furthermore, the C-F bond cleavage of the resulting α-fluoroaldehydes proceeded smoothly under alcoholic alkaline conditio
A simple primary amine catalyst for enantioselective α-hydroxylations and α-fluorinations of branched aldehydes
Witten, Michael R.,Jacobsen, Eric N.
supporting information, p. 2772 - 2775 (2015/06/16)
A new primary amine catalyst for the asymmetric α-hydroxylation and α-fluorination of α-branched aldehydes is described. The products of the title transformations are generated in excellent yields with high enantioselectivities. Both processes can be performed within short reaction times and on gram scale. The similarity in results obtained in both reactions, combined with computational evidence, implies a common basis for stereoinduction and the possibility of a general catalytic mechanism for α-functionalizations. Promising initial results in α-amination and α-chlorination reactions support this hypothesis.
