Naoki Manta

Bio: Naoki Manta is an academic researcher from Kwansei Gakuin University. The author has contributed to research in topics: Dieckmann condensation & Carboxylate. The author has an hindex of 3, co-authored 6 publications receiving 45 citations.

Practical Short Synthesis of 1β‐Methylcarbapenem Utilizing a New Dehydration Type Ti‐Dieckmann Condensation

Abstract: An efficient, practical, and stereocontrolled synthesis of 1β-methylcarbapenems has been performed utilizing a new dehydration type of Ti-Dieckmann (intramolecular Ti-Claisen) condensation. This cyclization reaction has the advantage of direct incorporation of the thiol moiety into the target 1β-methylcarbapenem, compared with the traditional basic Dieckmann condensation. Another advantage is the use of environmentally benign (low toxicity and safe) reagents (TiCl4 and Et3N or Bu3N).

Regioselective synthesis of methyl 3-thiothiophene-2-carboxylate derivatives utilizing a dehydration-type Ti-Dieckmann condensation

Abstract: Regioselective dehydration-type Ti-Dieckmann condensation of 3-(methoxycarbonylmethylthio)propanethioates successfully afforded methyl thiophene-2-carboxylates and methyl 4,5-dihydrothiophene-2-carboxylates, utilizing TiCl 4 - Et 3 N and TiCl 4 - (sec-Bu) 2 NH, respectively.

Practical Short Synthesis of 1β-Methylcarbapenem Utilizing a New Dehydration Type Ti-Dieckmann Condensation.

Abstract: An efficient, practical, and stereocontrolled synthesis of 1β-methylcarbapenems has been performed utilizing a new dehydration type of Ti-Dieckmann (intramolecular Ti-Claisen) condensation. This cyclization reaction has the advantage of direct incorporation of the thiol moiety into the target 1β-methylcarbapenem, compared with the traditional basic Dieckmann condensation. Another advantage is the use of environmentally benign (low toxicity and safe) reagents (TiCl4 and Et3N or Bu3N).

Ti-Crossed-Claisen Condensation between Carboxylic Esters and Acid Chlorides or Acids: A Highly Selective and General Method for the Preparation of Various β-Keto Esters

Abstract: Ti-crossed-Claisen condensation between a 1:1 mixture of carboxylic esters and acid chlorides promoted by TiCl4−Bu3N-N-methylimidazole proceeded successfully to give various β-keto esters in good yields with excellent selectivities (19 examples, ∼48−95% yield; cross/self-selectivity = ∼96/4−99/1). The present method was extended to the condensation between a 1:1 mixture of carboxylic acids and carboxylic esters (six examples, ∼70−92% yield; cross/self-selectivity = ∼91/9−99/1). To demonstrate the utility of the present two Ti-crossed-Claisen condensations, we performed a couple of efficient short-step syntheses of two natural, representative, and useful perfumes, cis-jasmone and (R)-muscone.

Lewis acid catalysis in supercritical carbon dioxide. Use of poly(ethylene glycol) derivatives and perfluoroalkylbenzenes as surfactant molecules which enable efficient catalysis in ScCO2.

Abstract: Lewis acid catalysis in supercritical carbon dioxide (CO(2)) was investigated. While solubility of most organic materials is low in scCO(2), poly(ethylene glycol) derivatives or perfluoroalkylbenzenes were found to work as surfactants to dissolve organic materials in scCO(2). In the presence of these molecules, Lewis acid catalyzed organic reactions such as aldol-, Mannich-, and Friedel-Crafts-type reactions proceeded smoothly in scCO(2). Formation of emulsions was observed in these reactions, and the systems were studied in detail.

Protecting-Group-Free Total Synthesis of (±)-Subincanadine F

Abstract: With chemoselective Dieckmann condensation as the key step, the protective-group-free total synthesis of (±)-subincanadine F was accomplished in 7 steps from the commercially available tryptamine in 33% overall yield.