scholarly journals Application of the Lithiation−Borylation Reaction to the Preparation of Enantioenriched Allylic Boron Reagents and Subsequent in Situ Conversion into 1,2,4-Trisubstituted Homoallylic Alcohols with Complete Control over All Elements of Stereochemistry

2010 ◽  
Vol 132 (16) ◽  
pp. 5922-5922 ◽  
Author(s):  
Martin Althaus ◽  
Adeem Mahmood ◽  
José Ramón Suárez ◽  
Stephen P. Thomas ◽  
Varinder K. Aggarwal
Keyword(s):  
Complete Control ◽  
Homoallylic Alcohols

Arrays of Stereogenic Centers: The Thomson Synthesis of (−)-Galactin

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
East China ◽  
Allylic Alcohols ◽  
University Of Texas ◽  
University Of New Mexico ◽  
Homoallylic Alcohols ◽  
Stereogenic Centers ◽  
Normal University ◽  
The University ◽  
Medical University

Hisashi Yamamoto of the University of Chicago and Chubu University developed (J. Am. Chem. Soc. 2014, 136, 1222) a tungsten catalyst for the enantioselective oxida­tion of allylic alcohols such as 1 to the epoxide 2. Homoallylic alcohols also worked well. Naoya Kumagai and Masakatsu Shibasaki of the Institute of Microbial Chemistry devised (Chem. Eur. J. 2014, 20, 68) a scalable Zn-catalyzed protocol for the coupling of 3 with 4 to give 5. Professor Shibasaki and Takumi Watanabe, also of the Institute of Microbial Chemistry, established (Org. Lett. 2014, 16, 3364) a Nb catalyst for the preparation of 8 by the Henry addition of 7 to 6. Wenhao Hu of East China Normal University effected (Synthesis 2014, 46, 1348) the coupling of 9 and 10 with two equivalents of aniline to give the diamine 10. Sanzhong Luo of the Institute of Chemistry, Beijing showed (Angew. Chem. Int. Ed. 2014, 53, 4149) that the adduct between 11 and an in situ formed N-nitroso could be reduced with high diastereoselectivity, leading to 12. Kumagai and Shibasaki also described (Angew. Chem. Int. Ed. 2014, 53, 5327) the assembly of 15 by the enantiose­lective addition 14 to 13. Bernhard Breit of the Albert-Ludwigs-Universität Freiburg effected (Synthesis 2014, 46, 1311) the carbonylation of the alkene 16 to give an alde­hyde that underwent in situ condensation with the imine 17, leading, after a subse­quent addition of vinyl magnesium chloride, to the lactone 18. Michael J. Krische of the University of Texas prepared (J. Am. Chem. Soc. 2014, 136, 8911) the diol 21 by adding the racemic epoxide 20 to the aldehyde 19. Martin Hiersemann of the Technische Universität Dortmund achieved (J. Org. Chem. 2014, 79, 3040) high enantioselectivity in the rearrangement of the enol ether 22 to 23. Michael T. Crimmins also observed (Org. Lett. 2014, 16, 2458) high ste­reocontrol in the rearrangement of 24 to 25. Wannian Zhang and Chunquan Sheng of the Second Military Medical University and Wei Wang of the University of New Mexico and the East China University of Science and Technology added (Org. Lett. 2014, 16, 692) the diketone 26 to the aldehyde 6 to give an intermediate adduct, that further cyclized to 27.

A tripartite asymmetric allylboration ? Silicon tethered alkene ring closing metathesis ? in situ ring opening protocol for the regiospecific generation of functionalized (E)-disubstituted homoallylic alcohols

Tetrahedron ◽  
1999 ◽  
Vol 55 (11) ◽  
pp. 3219-3232 ◽  
Author(s):  
Mahmood Ahmed ◽  
Anthony G.M. Barrett ◽  
Jennifer C. Beall ◽  
D. Christopher Braddock ◽  
Kevin Flack ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Closing Metathesis ◽  
Homoallylic Alcohols

Diastereoselectivity in asymmetric allylations: The role of vicinal chirality in the allyl nucleophile for SE2′ reactions with aldehydes

2004 ◽  
Vol 82 (2) ◽  
pp. 120-130 ◽  
Author(s):  
David R Williams ◽  
Kevin G Meyer ◽  
Khalida Shamim ◽  
Samarjit Patnaik
Keyword(s):  
Chiral Auxiliary ◽  
Asymmetric Allylation ◽  
Relative Significance ◽  
Homoallylic Alcohols ◽  
In Situ Formation

A series of nonracemic homoallylic alcohols have been prepared by asymmetric allylation using the (R,R)- and (S,S)-1,2-diamino-1,2-diphenylethane bis-sulfonamide controller ligands for in situ formation of chiral B-allyl-1,3,2-diazaborolidines. Diastereofacial selectivity is influenced by adjacent stereochemistry incorporated into the allyl moiety at C-2, in addition to the expected role of the chiral auxiliary. Additional asymmetry in the aldehyde reactant introduces threefold stereodifferentiation. A model is developed to identify reinforcing stereochemical relationships, and examples have ascertained the relative significance of these factors. The methodology supports the construction of complex homoallylic alcohols in a highly convergent fashion.Key words: asymmetric allylation, diastereofacial selectivity, 1,4-stereocontrol, homoallylic alcohols.

scholarly journals NbCl5-Mg Reagent System in Regio- and Stereoselective Synthesis of (2Z)-Alkenylamines and (3Z)-Alkenylols from Substituted 2-Alkynylamines and 3-Alkynylols

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3722
Author(s):  
Rita N. Kadikova ◽  
Azat M. Gabdullin ◽  
Oleg S. Mozgovoj ◽  
Ilfir R. Ramazanov ◽  
Usein M. Dzhemilev
Keyword(s):  
Double Bond ◽  
Stereoselective Synthesis ◽  
Efficient Tool ◽  
Magnesium Metal ◽  
Methanesulfonyl Chloride ◽  
Homoallylic Alcohols ◽  
Homopropargylic Alcohols ◽  
Stereoselective Method ◽  
High Yields

The reduction of N,N-disubstituted 2-alkynylamines and substituted 3-alkynylols using the NbCl5–Mg reagent system affords the corresponding dideuterated (2Z)-alkenylamine and (3Z)-alkenylol derivatives in high yields in a regio- and stereoselective manner through the deuterolysis (or hydrolysis). The reaction of substituted propargylamines and homopropargylic alcohols with the in situ generated low-valent niobium complex (based on the reaction of NbCl5 with magnesium metal) is an efficient tool for the synthesis of allylamines and homoallylic alcohols bearing a 1,2-disubstituted double bond. It was found that the well-known approach for the reduction of alkynes based on the use of the TaCl5-Mg reagent system does not work for 2-alkynylamines and 3-alkynylols. Thus, this article reveals a difference in the behavior of two reagent systems—NbCl5-Mg and TaCl5-Mg, in relation to oxygen- and nitrogen-containing alkynes. A regio- and stereoselective method was developed for the synthesis of nitrogen-containing E-β-chlorovinyl sulfides based on the reaction of 2-alkynylamines with three equivalents of methanesulfonyl chloride in the presence of stoichiometric amounts of niobium(V) chloride and magnesium metal in toluene.

Reconstruction of Carbon Bond Frameworks via Oxapalladacycle Promoted by Synergistic Effect of Palladium Catalyst and Triethylborane

Synthesis ◽  
2021 ◽  
Author(s):  
Ryo Ninokata ◽  
Riho Korogi ◽  
Junya Nakao ◽  
Tsutomu Fukuda ◽  
Gen Onodera ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Palladium Catalyst ◽  
Aldol Reaction ◽  
Conjugated Dienes ◽  
Prins Reaction ◽  
Carbon Bond ◽  
Unsaturated Aldehydes ◽  
Homoallylic Alcohols ◽  
Diastereomeric Mixture

Pd-catalyzed β-carbon elimination of 3-hydroxy-4-pentenoic acid derivatives promoted by triethylborane proceeded to form conjugated dienes via a decarboxylation process. The formed conjugated dienes underwent the Prins reaction with aldehydes in situ to afford conjugated homoallylic alcohols. These sequential transformations enabled conversion of a diastereomeric mixture of 3-hydroxy-4-pentenoic acids, which were readily prepared from the simple crossed aldol reaction of esters and α,β-unsaturated aldehydes, to 3,5-hexadienyl alcohols with high regio- and stereoselectivities in a single manipulation.

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