A New Nucleophilic Addition/Ring-Closure Sequence. Enantioselective Synthesis of 3-Deoxy-8-oxatropanes

2004 ◽  
Vol 6 (6) ◽  
pp. 893-895 ◽  
Author(s):  
Giang Nguyen ◽  
Patrick Perlmutter ◽  
Mark L. Rose ◽  
Filisaty Vounatsos
Keyword(s):  
Nucleophilic Addition ◽  
Enantioselective Synthesis ◽  
Ring Closure

The NARC-Based Approach to the Enantioselective Synthesis of the Zaragozic Acids. Synthesis of a C 5-Alkoxycarbonyl-Substituted 2,8-Dioxabicyclo[3.2.1]octane.

2000 ◽  
Vol 53 (4) ◽  
pp. 349 ◽  
Author(s):  
Patrick Perlmutter ◽  
Walailak Selajarern
Keyword(s):  
Nucleophilic Addition ◽  
Direct Method ◽  
Enantioselective Synthesis ◽  
Ring Closure ◽  
Zaragozic Acids ◽  
A Direct Method

A direct method for the preparation of C 5-alkoxycarbonyl-substituted 2,8-dioxabicyclo[3.2.1]octanes is described. The key process involves a highly stereoselective (NARC) sequence of a nucleophilic addition followed by ring closure.

scholarly journals Catalytic Enantioselective Synthesis of 4-Amino-1,2,3,4-tetrahydropyridine Derivatives from Intramolecular Nucleophilic Addition Reaction of Tertiary Enamides

Synlett ◽  
2018 ◽  
Vol 30 (04) ◽  
pp. 483-487 ◽  
Author(s):  
Shuo Tong ◽  
Mei-Xiang Wang
Keyword(s):  
Phosphoric Acid ◽  
Asymmetric Catalysis ◽  
Nucleophilic Addition ◽  
Addition Reaction ◽  
Enantioselective Synthesis ◽  
Chiral Phosphoric Acid ◽  
Substrate Engineering ◽  
Nucleophilic Addition Reaction ◽  
Engineering Strategy ◽  
Acid Catalyzed

A general and efficient method for the synthesis of highly enantiopure 4-amino-1,2,3,4-tetradydropyridine derivatives based on chiral phosphoric acid catalyzed intramolecular nucleophilic addition of tertiary enamides to imines has been developed. We have also demonstrated a substrate engineering strategy to significantly improve the enantioselectivity of asymmetric catalysis

Novel enantioselective synthesis of (S)-ketamine using chiral auxiliary and precursor Mannich base

2019 ◽  
Vol 97 (5) ◽  
pp. 331-336 ◽  
Author(s):  
Seyed Jamaladdin Gohari ◽  
Abdollah Javidan ◽  
Abolghasem Moghimi ◽  
Mohammad Javad Taghizadeh ◽  
Maryam Iman
Keyword(s):  
Acid Solution ◽  
Nucleophilic Addition ◽  
Grignard Reagent ◽  
Mannich Base ◽  
Enantioselective Synthesis ◽  
Chiral Auxiliary ◽  
Chiral Auxiliaries ◽  
Anesthetic Drug ◽  
Directing Group ◽  
High Yields

Ketamine has been extensively used as an anesthetic drug. Chiral auxiliaries such as tert-butanesulfinamide (TBSA) can be used for the asymmetric synthesis of (S)-ketamine. Condensation of TBSA with ketones provides tert-butanesulfinylimines in consistently high yields. The tert-butanesulfinyl group actuates the imine for nucleophilic addition, is a potent chiral directing group, and after nucleophilic addition is easily dissociated by intervention with acid solution. To prepare 2-(N-piperidinomethyl)-1-phenylcyclohexylamine (1), we started with the cyclohexanone and using Mannich reaction achieved an aminoketone. Then, we made the sulfiniylamin (2) by the condensation of TBSA with aminoketone. By using salts such as Ti(OEt)4, we obtained N-tert-butanesulfinylketimine in 85% yield. Next, we provided a new chiral center (3) using Grignard reagent as nucleophile at −78 °C (80% yield). Finally, after many steps, the (S)-ketamine synthesized under ozonolysis conditions, with good yield and enantioselectivity (75% yield and 75% ee).

scholarly journals Towards stereochemical control: A short formal enantioselective total synthesis of pumiliotoxins 251D and 237A

2013 ◽  
Vol 9 ◽  
pp. 2358-2366 ◽  
Author(s):  
Jie Zhang ◽  
Hong-Kui Zhang ◽  
Pei-Qiang Huang
Keyword(s):  
Total Synthesis ◽  
Enantioselective Synthesis ◽  
Ring Closure ◽  
Enantioselective Total Synthesis ◽  
Stereochemical Control ◽  
Stereoselective Addition ◽  
Methylmagnesium Iodide

A concise enantioselective synthesis of the advanced intermediate 5 for the synthesis of pumiliotoxins (Gallagher’s intermediate) is described. The synthesis started from the regio- and trans-diastereoselective (dr = 98:2) reductive 3-butenylation of (R)-3-(tert-butyldimethylsilyloxy)glutarimide 14. After O-desilylation and Dess–Martin oxidation, the resulting keto-lactam 10 was subjected to a highly trans-stereoselective addition of the methylmagnesium iodide to give carbinol 11 as sole diastereomer. An efficient ring closure procedure consisting of ozonolysis and reductive dehydroxylation provided the indolizidine derivative 5, which completed the formal enantioselective total synthesis of pumiliotoxins 251D and 237A.

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