Masato Matsugi

An efficient sulfenylation of aromatics using highly active quinone mono O,S-acetal bearing a pentafluorophenylthio group

A facile sulfenylation of various aromatic nuclei was achieved by use of the novel sulfenylation reagent, the quinone mono O,S-acetal bearing a pentafluorophenylthio group. This reagent functions below 0°C in the presence of a catalytic amount of TMSOTf.

Additions of malononitrile radicals to alkenes under mild conditions using 2,2′-azobis-(2,4-dimethyl-4-methoxyvaleronitrile) (V-70) as an initiator

Abstract The attributes of 2,2′-azobis-(2,4-dimethyl-4-methoxyvaleronitrile) (V-70), which is an effective radical initiator at low temperature, in contrast to 2,2′-azobisisobutyronitrile (AIBN) are described.

An efficient methodology for the C–C bond forming radical cyclization of hydrophobic substrates in water: effect of additive on radical reaction in water

Abstract The combination of the water-soluble radical initiator, 2,2′-azobis[2-(2-imidazolin-2-yl)propane] (VA-061), water-soluble chain carrier, 1-ethylpiperidine hypophosphite (EPHP) and surfactant, cetyltrimethylammonium bromide (CTAB), was found to be the most suitable condition for effective radical cyclization in water for a variety of hydrophobic substrates. The effect of additives and surfactant in the radical cyclization reaction in water was also investigated.

Lipase-Catalyzed Domino Kinetic Resolution/Intramolecular Diels–Alder Reaction: One-Pot Synthesis of Optically Active 7-Oxabicyclo[2.2.1]heptenes from Furfuryl Alcohols and β-Substituted Acrylic Acids

The first lipase-catalyzed domino reaction is described in which the acyl moiety formed during the enzymatic kinetic resolution of furfuryl alcohols (+/-)-3 with a 1-ethoxyvinyl ester 2 was utilized as a part of the constituent structure for the subsequent Diels-Alder reaction. The preparation of ester 2 from carboxylic acid 1 and the subsequent domino reaction were carried out in a one-pot reaction. Therefore, this procedure provides a convenient preparation of the optically active 7-oxabicyclo[2.2.1]heptene derivatives 5, which has five chiral, non-racemic carbon centers, from achiral 1 and racemic 3. The overall efficiency of this process was dependent on the substituent at the C-3 position of 3, and the use of the 3-methylfurfuryl derivatives, (+/-)-3 b and (+/-)-3 f, exclusively produced diastereoselectivity with excellent enantioselectivity to give (2R)-syn-5 (91->/=99 % ee) and (S)-3 (96->/=99 % ee). Similar procedures starting from the 3-bromofurfuryl alcohols (+/-)-3 h-j provided the cycloadducts (2R)-syn-5 j-q (93->/=99 % ee), in which the bromo group was utilized for the installation of bulky substituents to the 7-oxabicycloheptene core.

Determination of absolute configuration of trans-2-arylcyclohexanols using remarkable aryl-induced 1H NMR shifts in diastereomeric derivatives

Abstract A facile determination of the absolute configuration of trans-2-arylcyclohexanols was achieved. It takes advantage of the observations of the remarkable aryl-induced 1H NMR shifts that seems to be ascribable to the discrimination of the diastereo-environment between intermediary optically active diastereomers by intramolecular CH/π interaction.

Highly asymmetric Pummerer-type reaction induced by ethoxy vinyl esters

Abstract Ethoxy vinyl esters (EVE: 2 ) were efficient reagents for promoting the asymmetric Pummerer reaction with high enantioselectivity and high yield in contrast to the generally used acid anhydrides. Increasing the electron-donating ability on the R function in EVE 2 tended to increase enantioselectivity. Consequently, effective asymmetric rearrangements were achieved using EVEs 2b,c bearing a methoxybenzoyloxy function.

A highly stereoselective synthesis of α-linked C-glycopyranosides using 2,2′-azobis-(2,4-dimethyl-4-methoxyvaleronitrile) (V-70)

Abstract α-Linked C-glycopyranosides were obtained effectively by the radical addition reaction using V-70, an effective radical initiator under mild conditions.

Determination of stereochemistry and separation of diastereomeric derivatives of trans-2-pyridylcyclohexanols by extraction

Abstract The example of the determination of the stereochemistry and separation of diastereomeric derivatives of trans-2-pyridylcyclohexanols by extraction is shown here. The facile separation of the corresponding diastereomers is based on a difference in the basicity of the diastereomers.

A novel determination method of the absolute configuration of 1-aryl-1-alkylalcohols and amines by an intramolecular CH/π shielding effect in 1H NMR

Abstract A novel method for determination of the absolute configuration of various 1-aryl-1-alkylalcohols and amines was achieved by the observation of an intramolecular CH/π shielding effect in 1 H NMR. ( S )-Isomer of the diastereomers always shows effective shielding effect.

Efficient stereoselective synthesis of α-C-glycopyranosides using 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70]

Abstract Efficient synthesis of α - C -glycopyranosides through a radical addition reaction using 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile) [V-70] as an initiator under mild condition was developed. This method made it possible to completely control the stereocenter at the anomeric position and obtain only the α-anomer in high yield compared with AIBN, Et 3 B, and photo irradiation methods.