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One-pot synthesis of unsymmetrical aryl methylphosphinates by insertion of dichlorophosphines into the O-Me bond of anisoles
No full textThis letter describes a new one-pot method for the synthesis of unsymmetrical aryl methylphoshinates by insertion of phosphorus moiety into the O-Me bond of anisoles. These products are very difficult to obtain with other reported methods requiring several steps. © 2001 Elsevier Science Ltd. All rights reserved
New feature of Friedel-Crafts phosphonation of anisoles: Unexpected in situ methylphosphorylation reaction
No full textAnisoles 1, reacting with AlCl3 and PCl3 with appropriate reagent ratios, give, in good yields, the corresponding diaryl methylphosphonates 2 or the methylphoshinates 3b,c and the methylphosphine oxides 4b,c. This unexpected in situ methylphosphorylation explains the reported limited and conflicting results to obtain methoxy-substituted arylphosphonous dichloride with the same reagents. A suggested mechanism is also reported
A one-pot synthesis of 1-substituted cyclic phosphine sulfides by simultaneous addition of bis- and mono-grignard reagents to a new efficient phosphorus donating reagent
No full textThe synthesis of the reported cyclic phosphine sulfides (4, 5, 6) is carried out in good yields in a one-pot reaction with simultaneous addition of the three reagents (1, BrMgCH2(CH2)(n)CH2MgBr, RMgBr) and final treatment with sulfur. The new phosphorus donating reagent benzothiadiphosphole 1 is an inexpensive, facile to prepare, and air-insensitive solid
An efficient procedure for the synthesis of N-alkenyl derivatives of six-membered and larger 1,2-diaza heterocycles
No full textThe use of diazaphosphole derivatives generated in situ or the PCl3/hydrazone combination can be applied in a novel efficient one-pot procedure for the synthesis at room temperature of the title six-, seven- and eight-membered rings using always high concentration of the reagents (0.2-0.5 M). N-alkenyl derivatives of 1,2-diazaheterocycles such as 8 (perhydro-pyridazine-3,6-diones), 9 (perhydro-1,2-diazepin-3,7-diones), 10 (perhydro-1,2-diazocin-3,8-diones) and 11 (1,2-dihydro-pyridazine-3,6-diones) were obtained by reaction of PCl3, ketone methylhydrazones and succinic, glutaric, adipic and maleic acids respectively. Changing the order of addition of reagents, or their simultaneous addition, gave identical results. In all the procedures the yields were good. The exclusive or prevalent formation of the E isomer was always observed. The E-configuration of the exocyclic double bond was deduced from some NOE experiments carried out on a E,Z mixture obtained by isomerization of the E isomer
PCl3 mediated cyclization: Synthesis, at room temperature, of N-alkenyl derivatives of 1,4-phthalazinedione
No full textThe use of a PCl3/hydrazone/dicarboxylic acid combination can be applied in an efficient one-pot procedure for the synthesis at room temperature of the title ring compounds that are also a new family of stable enamines. The phthalazinediones 7 were obtained in good yields by reaction of PCl3 with phthalic acid and hydrazones 1a,b,c containing hydrogen atoms only in one a position. Two structurally isomeric phthalazinediones (7 and 8) were obtained with hydrazones 1d,e,f,g containing hydrogen atoms in the two different a positions. When we used a methyl ketone hydrazone 1c,d,e,f,i, it was possible also to isolate the isomer containing an N-alkenyl group with two terminal hydrogen atoms. Where E,Z isomers are possible, the exclusive formation of the E isomer was always observed. As a rule, changing the order of addition of reagents gave almost identical results; however, in the case of phthalic acid, it is better to use the procedure in which PCl3 is added last to prevent the formation of the corresponding anhydride. © 1999 John Wiley & Sons, Inc
An improved synthesis of fused 1,2,3-benzqthiadiphospholes and a proposed reaction pathway
No full textA fresh look has been taken at the reaction of PCl3 with thioanisole 1b and AlCl3 that gives, after treatment with water, the title compounds cis5-2b in 38% yield together with small amounts of the isomeric czs-3b (2%). The course of this reaction has been studied by 31P-NMR spectroscopy. A multistept pathway, governed by the formation of several AlCl3 complexes with sulfur and phosphorus containing intermediates, has been proposed. The crucial step of this reaction is very reasonably an intramolecular electrocyclic ring closure of a diphosphane intermediate. From this plausible mechanism, an improved procedure that gives only the cis-2b isomer in 42% yield has been realized. In addition, an alternative synthesis using p-thiocresol that gives compounds cis-2b and czs-3b in a ratio of about 2:1 has been effected. ©1997 John Wiley & Sons, Inc
PCl3-mediated cyclization: Synthesis at room temperature of N-alkenyl derivatives of perhydro-1,4,5-oxa(and thia)diazepine-3,6-dione and of 6,7-diazaspiro[3.4]octane-5,8-dione
No full textThe use of the PCl3/hydrazone/dicarboxylic acid combination can be applied in an efficient one-pot procedure for the synthesis at room temperature of the seven-membered ring compounds, 6 (perhydro-1,4,5-oxadiazepine-3,6-diones) and 7 (perhydro-1,4,5-thiadiazepine-3,6-diones), and of the first reported derivatives of the heterocycle 6,7-diazaspiro[3.4]octane-5,8-dione 8. Compounds 6 and 1, containing an N-alkenyl group, were obtained in good yields using diglycolic and thiadiglycolic acids with PCl3 and methylhydrazone 1, with use of a high concentration (0.5 M) of the reagents. N-alkenyl derivatives 8 were obtained in the same manner using 1,1-cyclobutanedicarboxylic acid. Changing the order of addition of the reagents gave almost identical results. In the case in which the exocyclic double bond can give E,Z-isomers, the exclusive or prevalent formation of the E-isomer was always observed. © 1999 John Wiley & Sons, Inc
New general one-pot synthesis of 1-alkoxy cyclic phosphine derivatives
No full textTreatment, at room temperature, of benzothiadiphosphole 1 with bis-Grignard 2, sodium alcoholate and finally with S8 afforded 1-alkoxy cyclic phosphine sulfides in good yields. In a similar manner, reactions with sodium phenylthiolate gave the corresponding 1-phenylsulfanyl cyclic phosphine derivatives
A new performance of the reaction of PCl3/AlCl3 with anisoles - One-pot and multi-step syntheses of a new fused-ring system [1,2,3]benzoxadiphospholo[2,3-b][1,2,3]benzoxadiphosphole
No full textAnisoles 4 react with AlCl3 and PCl3 to yield the new fused bicyclic system derivatives 5 and 6 as major products in a one-pot procedure. An alternative multi-step synthesis of this system is also reported in which bis(o-methoxyaryl)phosphane oxides 11 are treated with AlCl3 and PCl3; the diarylphosphane oxides 11 are obtained by a new simple method. © Wiley-VCH Verlag GmbH, 2001
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