146337-41-9Relevant academic research and scientific papers
Studies on the aza-Claisen rearrangement of 7 to 9-membered vinylazacycles
Kim, Seok-Ho,Lee, Won-Il,Kim, Seon-Mi,Jung, Jae-Kyung,Jang, Jaebong,Sim, Jaehoon,Jung, Jong-Wha,Suh, Young-Ger
, p. 886 - 899 (2016/07/06)
A systematic study on the amide enolate-induced aza-Claisen rearrangement (ACR) of 7 to 9-membered vinylazacycles has been carried out, resulting in an efficient synthetic method to prepare 11 to 13-membered macrolactams. Key feature includes introduction of electron-donating substituents at α-position of the amide substrates possessing 7 to 9-membered vinylazacycles to facilitate amide enolate-induced ACR. In addition, substituent effects on ACR has been discussed based on the experimental results. We believe this study would provide experimental evidences for the substituent effects and envision for the synthetic application of ACR-induced ring expansion.
α-Lithioamine Synthetic Equivalents: Synthesis of Diastereoisomers from Boc Derivatives of Cyclic Amines
Beak, Peter,Lee, Won Koo
, p. 1109 - 1117 (2007/10/02)
Sequences of α'-lithiations and electrophilic substitutions of Boc-pyrrolidines, Boc-piperidines, and Boc-hexahydroazepines that provide compounds which are substituted adjacent to nitrigen are reported, and the pathways of the reactions are discussed.By this methodology monosubstituted 2 and disubstituted 2,4, 2,6, and 2,5 Boc-piperidines are obtained as single or separable diastereoisomers consistent with equatorial lithiations and retentive electrophilic substitution in chair conformations.Both cis and trans 2,6-disubstituted diastereoisomers can be prepared, and control of diastereoselectivity is demonstrated by syntheses of solenopsin A, a 2,6-trans-disubstituted piperidine, and of Boc-dihydropinidine, a 2,6-cis-disubstituted piperidine.In the case of 3-methoxy-Boc-piperidine elimination of methoxide occurs upon lithiation, and with cis-2,4-disubstituted Boc-piperidines the electrophile is introduced with trans stereochemistry at C-6.These reactions are suggested to involve twist boat conformations consistent with an X-ray crystal structure of 2-methyl-6-(trimethylstannyl)-4-phenyl-N-Boc-piperidine.Boc-pyrrolidine lithiates more rapidly than Boc-piperidine, provides 2-substituted products with electrophiles, and on further lithiation-substitution gives 2,5-cis- and -trans substituted products.Boc-perhydroazepine provides 2-substituted products by the sequence and on further lithiation-substitution gives 2,7-trans-disubstituted products.
