ChemInform Abstract: Folding Strain Stereocontrol in Cyclohexane Ring Formation by Means of an Intramolecular Ester Enolate Alkylation Reaction.

ChemInform ◽  
2010 ◽  
Vol 28 (27) ◽  
pp. no-no
Author(s):  
T. TOKOROYAMA ◽  
H. KUSAKA
Keyword(s):  
Ring Formation ◽  
Cyclohexane Ring ◽  
Alkylation Reaction ◽  
Enolate Alkylation ◽  
Ester Enolate

Folding strain stereocontrol in cyclohexane ring formation by means of an intramolecular ester enolate alkylation reaction

1996 ◽  
Vol 74 (12) ◽  
pp. 2487-2502 ◽  
Author(s):  
Takashi Tokoroyama ◽  
Hisashi Kusaka
Keyword(s):  
Stereoselective Synthesis ◽  
High Selectivity ◽  
Ring Closure ◽  
Alkylation Reaction ◽  
Qualitative Comparison ◽  
Enolate Alkylation ◽  
Leaving Group ◽  
Counter Cation ◽  
Ester Enolate ◽  
C Nmr

Diastereoselectivity in the cyclization of ethyl 7-bromo-2-methylheptanoates with an additional substituent at various positions in the chain, by LDA treatment, was investigated in connection with the concept of folding strain stereocontrol. Cyclization of 3-, 4-, and 6-methyl-substituted substrates revealed high selectivity, which demonstrates the prevalence of folding strain stereocontrol and the usefulness of this approach for stereoselective ring construction. In particular, reactions of the latter two substrates resulted in the stereodivergent preparation of diastereomeric 1,3-dimethylcyclohexanecarboxylates. In the case of the 5-mefhyl-substituted substrate, the selectivity of ring closure was only moderate. 1H and 13C NMR spectroscopic data were useful for determining the conformation of 1 -methylcyclohexanecarboxylate derivatives. The origin of the diastereoselectivity was examined through the qualitative comparison of the strain in the diastereomeric folding in the transition state. Various factors that might affect stereoselectivity were examined in the cyclization of 5-substituted substrates to better understand this concept. As predicted, the selectivity increased as the substituent became bulkier: Ph < Me ≈ Et < i-Pr < t-Bu. The effects of other factors — solvent, base counter cation, and leaving group — on selectivity agree with results predicted from the reactivity–selectivity relationship. Key words: folding strain stereocontrol; diastereoselectivity in ring-closure reaction; remote asymmetric induction; ethyl 2-methylcyclohexanecarboxylate derivatives, 1H and 13C NMR; stereoselective synthesis of substituted cyclohexane derivatives.

A total synthesis of (−)-reiswigin a via sequential claisen rearrangement-intramolecular ester enolate alkylation

1994 ◽  
Vol 35 (43) ◽  
pp. 7957-7960 ◽  
Author(s):  
Deukjoon Kim ◽  
Kye Jung Shin ◽  
Ik Yoen Kim ◽  
Sang Woo Park
Keyword(s):  
Total Synthesis ◽  
Claisen Rearrangement ◽  
Enolate Alkylation ◽  
Ester Enolate

A stereoselective synthesis of (±)-elemol via an intramolecular SN2′ ester enolate alkylation

1993 ◽  
Vol 34 (41) ◽  
pp. 6557-6558 ◽  
Author(s):  
Deukjoon Kim ◽  
Joong In Lim ◽  
Kye Jung Shin ◽  
Hak Sung Kim
Keyword(s):  
Stereoselective Synthesis ◽  
Enolate Alkylation ◽  
Ester Enolate

Stereoselective construction of steroidal trans-hydrindanes via intramolecular ester enolate alkylation[1,2]

1990 ◽  
Vol 31 (28) ◽  
pp. 4027-4028 ◽  
Author(s):  
Kim Deukjoon ◽  
Kim Sanghee ◽  
Jeong Lee Jae ◽  
Sung Kim Hak
Keyword(s):  
Enolate Alkylation ◽  
Ester Enolate
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