Jean-Marc Clavel

Sur la transformation du β-nitrostyrène sous l'action du chlorure d'acétyle en présence d'un chlorure métallique

Abstract While β-nitrostyrene yields only hydroxymic or hydroxamic acid derivatives by treatment with acetyl chloride in the presence of zinc, tin, titanium or aluminium chloride, it also gives 3-chloro 2-indolinone and a 5-acetyl derivative of the latter, when the reaction is carried out with ferric chloride. The procedures of this reaction are examined, and a mechanism is suggested.

Sur une transformation inhabituelle de nitro-2 benzofurannes dans les conditions de la reaction de friedel et crafts

Abstract On treatment with acetyl chloride or acetic anhydride in presence of aluminium chloride in methylene chloride. 2-nitro and 5-chloro 2-nitro benzofurans yield 2,3-dichloro benzofurans, 3-chloro 2-coumaranones and 2-acetoximino 3-chloro coumarans. By the action of acetyl chloride, in presence of titanium (IV) chloride in methylene chloride, on 2-nitro benzofuran, 2,3-dichloro benzofuran can be obtained with a fairly good yield beside a relatively restricted quantity of 3-chloro 2-coumaranone. In the same conditions, 5-chloro-2-nitro benzofuran yields not only 2,3,5-trichloro benzofuran but also 2,2,3,3,5-pentachloro coumaran and, occasionally. 3,5-dichloro 2-coumaranone.

Recherches sur le benzofuranne. LVI. Synthèses dans la série de l'Euparone par acétylation de benzofurannes acétylés et méthoxylés sur l'homocycle †

Les derives acetyles et methoxyles sur lhomocycle de benzofurannes non substitues sur rheteroeycle peuvent ětre acetyles soil sur lhomocycle, soit sur lheterocycle, avec ou sans demethylation selon les eas. On forme ainsi, avec des rendements satisfaisants, une serie de nouveaux isomeres de lEuparone (diacetyl-2,5 hydroxy-6 benzofuranne) et de lether methylique correspondant. n n n nUnsubstituted benzofuran derivatives acetylatcd and methoxy-lated on the benzenoid moiety can be further acetvlated either on the benzene or on the furan ring - with or without demethylation depending upon the different cases. A series of new isomers of Euparone (2,5-diacetyl-6-hydroxybenzofuran) and its corresponding ether has thus been formed.

A Synthetic Approach to the Glycan Chain of High Mannose Type N-Glycoprotein

Abstract The syntheses of α-D-glucopyranose-(1→3)-D-mannopyranose, methyl α-D-glucopyranose-(1→3)-α-D-mannopyranoside and methyl α-D-glucopyranose-(1→3)-α-D-mannopyranose-(1→2)-α-D-mannopyranoside are reported. High stereoselectivity was observed during the coupling of glucose and mannose residues by the use of glucosyl trichloroacetimidate as donor.

SYNTHESIS OF THE TETRASACCHARIDE Glc α (1→3) Man α (1→2) Man α (1→2) Man α (OMe) AS INHIBITOR OF CALNEXIN BINDING TO GlcMan 9GlcNAc 2 a

Tetrasaccharide GlcMan 3 is an inhibitor of GlcMan 9GlcNAc 2 binding to calnexin, a chaperone protein involved in CFTR-ΔF 508 retention. A convergent route to its methyl glycoside, the title tetrasaccharide, was developed. The key building block Glc α (1→3) Man 6 was stereoselectively obtained by condensation of a trichloroacetimidate glucosyl donor with an ethyl thiomannopyranoside acceptor. Di-mannose moiety 10 and final compound 12 resulted from thioglycoside activations. a Dedicated to Prof. Joachim Thiem on the occasion of his 60th birthday.