Stereoselective Conversion of Stabilized Phosphorus Ylides to Dialkyl 2-(2-Nitro-phenoxy)-2-butenedioates in the Presense of Silica Gel in Solvent-Free Conditions
摘要:
Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 2-nitrophenol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce dialkyl 2-(2-nitro-phenoxy)-3-(triphenylphosphoranylidene)butanedioates. Silica-gel powder was found to catalyze the stereoselective conversion of dialkyl 2-(2-nitro-phenoxy)-3-(triphenylphosphoranylidene)butanedioates to dialkyl 2-(2-nitro-phenoxy)-2-butenedioates in solvent-free conditions under microwave (0.5 KW, 3 min) and thermal (90 degrees C, 60 min) conditions.
A process for producing a dicarboxylic acid compound represented by the formula (4):
wherein R
1
and R
2
are the same or different and each represents lower alkyl and the wavy line indicates that this compound is the E- or Z-isomer or a mixture of them, characterized by reacting a compound represented by the formula (2):
wherein R
1
, R
2
and the wavy line have the same meanings as the above, and one of X
2
and X
3
represents hydrogen and the other represents halogen, with nitrophenol represented by the formula (3):
in the presence of a base; a process for producing a nitrochromone compound represented by the formula (5):
wherein R
1
has the same meaning as the above, characterized by reacting the dicarboxylic acid compound or carboxylic acid thereof with an acid; a process for producing an aminochromone compound which comprises reducing the nitrochromone compound; and a process for producing an amidochromone compound which comprises acylating the aminochromone compound are provided.
A process for producing a dicarboxylic acid compound represented by the formula (4):
wherein R1 and R2 are the same or different and each represents lower alkyl and the wavy line indicates that this compound is the E- or Z-isomer or a mixture of them, characterized by reacting a compound represented by the formula (2):
wherein R1, R2 and the wavy line have the same meanings as the above, and one of X2 and X3 represents hydrogen and the other represents halogen, with nitrophenol represented by the formula (3):
in the presence of a base; a process for producing a nitrochromone compound represented by the formula (5):
wherein R1 has the same meaning as the above, characterized by reacting the dicarboxylic acid compound or carboxylic acid thereof with an acid; a process for producing an aminochromone compound which comprises reducing the nitrochromone compound; and a process for producing an amidochromone compound which comprises acylating the aminochromone compound are provided.
A process for producing a dihalosuccinic acid compound in which the proportion of a threo-dihalosuccinic acid compound is 70% or higher, which comprises adding a maleic acid compound to a halogenating agent.