A convenient access to variously substituted spiro[cyclopropane-1,4 '-oxazoline]s

作者：Dalai Suryakanta; Es Sayed Mazen; Noetzel Marcus; de Meijere Armin^*

来源：European Journal of Organic Chemistry, 2008, (21): 3709-3713.

DOI：10.1002/ejoc.200800333

• amides
• nitrogen heterocycles
• Michael addition
• Buchwald-Hartwig amination
• Suzuki coupling
• cycloproparies
• spiro compounds

Michael additions of carboxamides 2a-d under basic conditions onto methyl 2-chloro-2-cyclopropylidene acetate (1) with subsequent ring closure furnished the 4-spirocyclopropanated methyl oxazolinecarboxylates 3a-d (51-81% yields), from which the corresponding free carboxylic acids 4a-d were obtained by hydrolysis in excellent yield (89-93 %). Coupling reactions of 4a-d with different o-hydroxyaniline derivatives in the presence of HOAt/EDC and 2,4,6-collidine gave the anilides 5 in good to very good yields (55-92 %). The latter under Mitsunobu reaction conditions (Ph(3)P/DEAD) furnished the benzoxazole derivatives 6 (81-88 %). The bromine substituent in the N-methylated 4-spirocyclopropanated 2-(bromophenyl)oxazoline-5-carboxanilides 8c,d were aminated with various secondary amines under Buchwald-Hartwig reaction conditions to give the 2-(aminophenyl)oxazolinecarboxanilides 9 (12-90 %). Suzuki cross-couplings of 8c with arene- and hetareneboronic acids provided the oxazolines with 2-biaryl substituents 10-13 (65-90 %).

• 出版日期2008-7