- Simple deprotection of acetal type protecting groups under neutral conditions
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Heating acetals with ethylene glycol causes the deprotection of acetal type protecting groups. When acetals such as MOM ethers, MEM ethers, and THP ethers were heated in ethylene glycol or propylene glycol, solvolysis proceeded smoothly to produce alcohols in excellent yield. This reaction is a very promising method for chemoselective deprotection of acetal type protecting groups.
- Miyake, Hideyoshi,Tsumura, Takatsugu,Sasaki, Mitsuru
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- CLASS OF BIFUNCTIONAL COMPOUNDS WITH QUATERNARY AMMONIUM SALT STRUCTURE
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The invention provides a class of compounds represented by formula (I), having bifunctional active quaternary ammonium salt structure of a β2-adrenoreceptor agonist and an M receptor antagonist, a pharmaceutically acceptable salt, solvate, and optical isomer thereof. A pharmaceutical composition comprising such a compound with quaternary ammonium salt structure, a method for preparing such a compound with quaternary ammonium salt structure and an intermediate thereof, and uses thereof in treating pulmonary disorders are also provided. The compounds of the invention have high selectivity to the M receptor subtype, and have less adverse reaction and lower toxic and side effects in the treatment of pulmonary diseases such as COPD and asthma.
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Paragraph 0255
(2019/11/11)
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- Reactions of 4-Substituted-2'-Halogenoacetophenones with Grignard Reagents
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The initial reaction of 4-substituted 2'-halogenoacetophenones with an excess of methyl Grignard reagent is shown to be an attack at the 1'-carbonyl to form a halohydrin salt.The various reactions which then follow are substituent dependent.In the 4-hydroxy case the only product is 1-(4-hydroxyphenyl)-2-methylpropan-2-ol (13) which arises via a -aryl shift with simultaneous elimination of magnesium halide.When the substituent is 4-methoxy, a second pathway becomes important involving epoxide formation and a subsequent -hydride migration to the benzylic position, or attack of the Grignard reagent at the benzylic carbon of the epoxide.When the substituent is 4-bromo, the reaction proceeds exclusively via the epoxide and, following a -hydride shift, leads to the isomeric butanols (33) and (34).The reasons underlying such diversity of reactivity are discussed.
- Crombie, Leslie,Hardy, Robert,Knight, David W.
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p. 1373 - 1380
(2007/10/02)
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