Synthesis of a stable indium complex derived from γ-silyl-α,α-difluorobromopropyne: evaluation of experimental parameters
摘要:
Fluoroallenes, are potentially useful cyclization precursors because of the synergistic combination of fluorine's unique stereolectronic features and the rich chemistry of allenes. We have optimized the experimental conditions needed for the formation of a difluoropropargylindium complex 2. Sonication, lower reaction temperatures (5 degreesC), and dilute concentration of the starting material (0.15 M) are required to maximize production of this complex. Although the structure of this complex remains unknown, we have found that the nature of the alkyl substituents on the silyl group does not influence the formation of 2 but it does affects the allenyl 5 to propargyl 4 ratio. (C) 2004 Elsevier B.V. All rights reserved.
Regiospecific Synthesis of Bicyclo- and Heterobicyclo-<i>g</i><i>em</i>-difluorocyclobutenes Using Functionalized Fluoroallenes and a Novel Mo-Catalyzed Intramolecular [2 + 2] Cycloaddition Reaction
作者:Qilong Shen、Gerald B. Hammond
DOI:10.1021/ja0263893
日期:2002.6.1
The first synthesis of functionalized gem-difluoroallenes 4 served as platform for an unprecedented molybdenum-catalyzed intramolecular allene-alkyne [2 + 2]-cycloaddition that produced 6, a hitherto unknown class of bicyclo- and heterobicyclo-CF2-containing cyclobutenes.
Functionalization of Monofluoroallene and the Synthesis of Aryl-Substituted Conjugated Fluorodienes
作者:Yunfeng Lan、Gerald B. Hammond
DOI:10.1021/ol026196k
日期:2002.7.1
3a, prepared from 1, cyclized easily to 4 but preserved its fluoroallenyl integrity under oxidation and S(N)2 displacement to yield aldehyde, amine, mesylate, and halide 6. Allylic isomerization yielded 2-halo-1-fluoro-1,3-butadiene 7, which underwent a Suzuki coupling to give aryl-substituted conjugateddiene 8.
On the Nature of Organoindium Intermediates: the Formation of Readily Isolable Difluoropropargylindium Reagents and their Regioselectivity Towards Electrophilic Substitutions
作者:Bo Xu、Gerald B. Hammond
DOI:10.1002/chem.200801367
日期:2008.11.10
The structure and reactivity of intermediate propargylindium complexes have been investigated. Their reaction with electrophiles produced a difluoroalkyne or -allene, depending on the nature of the electrophiles. A mechanism based on the Curtin-Hammett principle was invoked to explain this phenomenon. A newly proposed mechanism on the formation of indium(III) complexes, through the intermediacy of
Highly Efficient Synthesis of 1,1-Difluoro-2-substituted-1,3-dienes and Dienynes from <i>g</i><i>em</i>-Difluorohomoallenyl Bromide via Palladium-Catalyzed Cross-Coupling Reactions
作者:Qilong Shen、Gerald B. Hammond
DOI:10.1021/ol0160654
日期:2001.7.1
[GRAPHICS]A stable gem-difluoroallenylindium 1 is readily transformed to a potentially bifunctional electrophile 2, which can then undergo a transition-metal-promoted isomerization-cross coupling cascade to yield diene 3 and dienyne 4 in very high yields.
Synthesis and X-ray information of substituted gem-difluoroallenyl amines
作者:Qilong Shen、Chbun-Hsing Chen、Gerald B. Hammond
DOI:10.1016/s0022-1139(02)00158-6
日期:2002.10
An O to N substitution in 4,4-difluorobutadiene-2,3-ol-1 has been accomplished in very satisfactory yields, and without compromising the gem-difluoroallenyl integrity, using modified Mitsunobu conditions. Recrystallization of the resulting tosyl-substituted amines furnished the first X-ray crystallographic analysis of difluoroallenes. (C) 2002 Elsevier Science B.V. All rights reserved.