共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Fuyuhiko Inagaki Dr. Syu Narita Takuma Hasegawa Shinji Kitagaki Dr. Chisato Mukai Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(11):2007-2011
No templates needed : The title reaction makes it easy to construct the bicyclo[6.3.0]undecadienone framework in high yields (see scheme). A template effect is not required to achieve this ring‐closing reaction efficiently. The present method can be applied to the construction of bicyclo[5.3.0] and bicyclo[4.3.0] ring systems. Ts=p‐toluenesulfonyl.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Fernanda M. Ribeiro Laia 《Tetrahedron letters》2009,50(45):6180-2356
The reactivity of buta-2,3-dienoates toward aziridines is reported. Allenoates react as 2π-component in the [3+2] cycloaddition with the azomethine ylide generated from cis-1-benzyl-2-benzoyl-3-phenylaziridine affording 4-methylenepyrrolidines in a site-, regio-, and stereoselective fashion. Under conventional thermolysis, cis- and trans-2-benzoyl-1-cyclohexyl-3-phenylaziridines showed a different reactivity. These aziridines participate in formal [3+2] cycloadditions with allenes via C-N bond cleavage of the three-membered ring leading to functionalized pyrroles. 相似文献
13.
14.
15.
16.
Biming Mao Honglei Liu Zhengyang Yan Yi Xu Jiaqing Xu Wei Wang Yongjun Wu Prof. Dr. Hongchao Guo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11412-11416
A palladium-catalyzed asymmetric [4+2] cycloaddition of 2-methylidenetrimethylene carbonate with alkenes derived from pyrazolones, indandione, or barbiturate has been successfully developed, affording pharmacologically interesting chiral tetrahydropyran-fused spirocyclic scaffolds. The target compounds were generated in good to excellent yields and with high enantioselectivity (up to 99 % ee). Furthermore, this cycloaddition reaction could be efficiently scaled up, and several synthetic transformations were accomplished for the construction of other useful chiral spiropyrazolone and spiroindandione derivatives. 相似文献
17.
Trost BM Shen HC Horne DB Toste FD Steinmetz BG Koradin C 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(8):2577-2590
The Ru-catalyzed intramolecular [5+2] cycloaddition of cyclopropylenynes is investigated with respect to the regio- and diastereoselectivity as well as the functional group compatibility of the reaction. Evidence for the mechanism as occurring through a ruthenacyclopentene intermediate is elucidated from 1) the study of the diastereoselectivity of the cycloaddition; 2) the effect of variation of substituents on the regioselectivity of cyclopropyl bond cleavage in 1,2-trans- and 1,2-cis-disubstituted cyclopropanes and 3) examples that clearly do not involve ruthenacyclohexene as intermediates as products still incorporate the cyclopropyl moiety. The scope and limitations of the Ru-catalyzed cycloaddition are discussed and compared with the Rh-catalyzed reaction. The potential power of this methodology towards natural product total synthesis is demonstrated by the formation of several polycyclic systems with the chosen reaction conditions and readily available cyclopropylenyne substrates. 相似文献
18.
19.
20.
1,5-Diphosphabicyclo [3.3.1]nonane 1,5-Diphosphabicyclo[3.3.1]nonane 8 has been obtained by free-radical cyclization of CH2?CHCH2(H)PCH2P(H)CH2CH?CH2 6 and 1-allyl-1,3-diphosphorinane 7 . For the synthesis of 6 and 7 the chlorophosphine Cl2PCH2PCl2 1 is used as a starting material, which can be converted into Me2N(Cl)PCH2P(Cl)NMe2 3 by reaction with (Me2N)2PCH2P(NMe2)2 2 . Treatment of 3 with two equivalents of allyl lithium and cleavage of the PN bonds in CH2?CHCH2(Me2N)PCH2P(NMe2)CH2CH?CH2 4 with diluted HCl affords CH2?CHCH2(H)(O)PCH2P(O)(H)CH2CH?CH2 5 . Phenylsilane is used for the first time as a reducing agent to obtain a secundary phosphine like 6 from the secundary phosphine oxide ( 5 ). Prolonged heating increases the yield of the byproduct 7 in the mixture of 6 and 7 . Reactions of the trivalent phosphorus in 8 with CS2, CH3I, POCl3, NO, sulfur, and KSeCN, respectively, delivers the corresponding derivatives 9–17 . The compounds decribed are characterized by 1H, 13C, 31P, 77Se n.m.r., i.r., and m.s. data. 相似文献