Inter- and Intramolecular Differentiation of Enantiotopic Dioxane Acetals through Oxazaborolidinone-Mediated Enantioselective Ring-Cleavage Reaction:  Kinetic Resolution of Racemic 1,3-Alkanediols and Asymmetric Desymmetrization ofMeso-1,3-polyols

2002 ◽  
Vol 67 (20) ◽  
pp. 7080-7090 ◽  
Author(s):  
Toshiro Harada ◽  
Takayuki Egusa ◽  
Yasuto Igarashi ◽  
Motoharu Kinugasa ◽  
Akira Oku
Keyword(s):  
Kinetic Resolution ◽  
Reaction Kinetic ◽  
Ring Cleavage ◽  
Cleavage Reaction

ChemInform Abstract: Kinetic Resolution of Cyclic Acetals Derived from 1,3-Alkanediols via Oxazaborolidine-Mediated Enantioselective Ring-Cleavage Reaction.

ChemInform ◽  
2010 ◽  
Vol 29 (42) ◽  
pp. no-no
Author(s):  
T. HARADA ◽  
T. EGUSA ◽  
M. KINUGASA ◽  
A. OKU
Keyword(s):  
Kinetic Resolution ◽  
Ring Cleavage ◽  
Cleavage Reaction ◽  
Cyclic Acetals

Kinetic resolution of cyclic acetals derived from 1,3-alkanediols via oxazaborolidine-mediated enantioselective ring-cleavage reaction

1998 ◽  
Vol 39 (31) ◽  
pp. 5531-5534 ◽  
Author(s):  
Toshiro Harada ◽  
Takayuki Egusa ◽  
Motoharu Kinugasa ◽  
Akira Oku
Keyword(s):  
Kinetic Resolution ◽  
Ring Cleavage ◽  
Cleavage Reaction ◽  
Cyclic Acetals

Pyrrole studies. Part 32. A novel ring-cleavage reaction of the pyridazine ring during the reaction of 6H-pyrrolo[3,4-d]pyridazines with dimethyl acetylenedicarboxylate

1985 ◽  
pp. 899 ◽  
Author(s):  
Teresa Hernandez de la Figuera Gomez ◽  
Jos� Sep�lveda Arques ◽  
R. Alan Jones ◽  
Helen M. Dawes ◽  
Michael B. Hursthouse
Keyword(s):  
Ring Cleavage ◽  
Dimethyl Acetylenedicarboxylate ◽  
Cleavage Reaction ◽  
Pyridazine Ring

Attempted enantiotopic group selective cyanohydrin formation from α-alkoxy aldehydes by double stereodifferentiation

2001 ◽  
Vol 79 (11) ◽  
pp. 1775-1785 ◽  
Author(s):  
Dale E Ward ◽  
Marcelo Sales ◽  
Matthew J Hrapchak
Keyword(s):  
Kinetic Resolution ◽  
Reaction Kinetic ◽  
Selective Reaction ◽  
The Poor

Enantiotopic group selectivity can result from the competition between substrate and reagent double stereodifferentiation. We have examined this approach for enantioselective hydrocyanation of racemic α-alkoxy aldehydes (e.g., 2-(phenylmethoxy)heptanal (1)). Reaction of 1 with TMSCN mediated by chiral nonracemic alkoxy Ti(IV) reagents under conditions known to be reasonably enantioface selective in reactions with achiral aldehydes, proceeded with very low enantiotopic group selectivity (<2:1). It was established that TMSCN can react with Ti(IV) reagents to produce "TiCN" adducts that are capable of hydrocyanation but with low substrate-controlled diastereoselectivity in reactions with 1. The poor enantiotopic group selectivity observed can be rationalized to result from this low diastereoselectivity despite the respectable levels of enantioface selectivity associated with these reagents in hydrocyanation of achiral aldehydes. Highly diastereoselective hydrocyanation of α-alkoxy aldehydes can be achieved with TMSCN in the presence of excess MgBr2·OEt2. High diastereoselectivity was also observed using achiral and chiral TiCN adducts in place of TMSCN. Although the putative TiCN adducts obtained from nonracemic alkoxy Ti(IV) reagents are implicated in enantioface selective hydrocyanation, these reagents were not enantiotopic group selective under these conditions and showed no evidence of double stereodifferentiation. The use of nonracemic bisoxazoline ligands for Mg(II) was also ineffective.Key words: cyanohydrin, 2-alkoxyalkanal, double stereodifferentiation, enantiotopic group selective reaction, kinetic resolution.

Chiral Oxazaborolidinone-Mediated Enantioselective Ring-Cleavage Reaction of a Mixture of Diastereomeric 1,3-Dioxolane Acetals: Application to Asymmetric Desymmetrization of meso-1,2-Diols

Synlett ◽  
2001 ◽  
Vol 2001 (01) ◽  
pp. 0061-0064 ◽  
Author(s):  
Toshiro Harada ◽  
Hideki Yamanaka ◽  
Akira Oku
Keyword(s):  
Ring Cleavage ◽  
Cleavage Reaction

ChemInform Abstract: A Palladium-Catalyzed, Abnormal Hydrogenolytic Ring Cleavage Reaction of Fused β-Lactams.

ChemInform ◽  
2010 ◽  
Vol 23 (38) ◽  
pp. no-no
Author(s):  
T. KONOSU ◽  
S. OIDA
Keyword(s):  
Ring Cleavage ◽  
Cleavage Reaction ◽  
Palladium Catalyzed
Sign in / Sign up

Export Citation Format

Share Document