کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
65192 48386 2015 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Green synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran and its subsequent enantioselective epoxidation
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Green synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran and its subsequent enantioselective epoxidation
چکیده انگلیسی


• Green synthesis of a 2-H-1-benzopyrans and its corresponding epoxide.
• Catalysts used were recovered and recycled.
• The partial substitution of protons by pyridine in H4PMo11VO40 was favorable to obtain 2-H-1-benzopyrans.
• The best chiral induction was obtained with S,S-Jacobsen using 4-phenylpyridine N-oxide as axial base and low temperature (4 °C).

The clean synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran epoxide starting from 3-methyl-2-butenal is reported using recyclable catalysts. H4PMo11VO40 (PMo11V) and (PyH)3HPMo11VO40 (Py3–PMo11V) Keggin-type heteropolyacids were used to synthesize 6-cyano-2,2-dimethyl-2-H-1-benzopyran in two steps with 35% yield. This is an alternative procedure to the traditional methodology with pyridine or picoline as catalyst, where 6-cyano-2,2-dimethyl-2-H-1-benzopyran is obtained by condensation of 4-cyanophenol with 1,1-diethoxy-3-methyl-2-butene. The 6-cyano-2,2-dimethyl-2-H-1-benzopyran epoxide was obtained using Jacobsen-type catalysts, and in situ generated dimethyldioxirane (DMD) as oxidizing agent, that in comparison to m-CPBA/4-NMO and NaOCl/4-PPNO did not degrade the catalyst. In presence of 4-phenylpyridine N-oxide (4-PPNO) at 4 °C, enantioselectivities of 87% for 3S,4S-epoxide and 68% for 3R,4R-epoxide were obtained with the S,S- and R,R-Jacobsen catalysts, respectively. Overall yield was approximately 17% for 3S,4S-epoxide.

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis A: Chemical - Volume 398, March 2015, Pages 11–16
نویسندگان
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