The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes

• Yi Wang,
• Peer Kirsch,
• Tomas Lebl,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2012, 8, 1271–1278, doi:10.3762/bjoc.8.143

• . This structure has two distinct types of methylene group, those located at corners of the ring and those at edges. Recently we prepared and explored the conformation of cyclododecane ring systems carrying either one or two difluoromethylene (CF2) groups in place of methylenes (CH2) [7]. The study

Novel synthesis of pseudopeptides bearing a difluoromethyl group by Ugi reaction and desulfanylation

• Jingjing Wu,
• Hui Li and
• Song Cao

Beilstein J. Org. Chem. 2011, 7, 1070–1074, doi:10.3762/bjoc.7.123

• building block 2,2-difluoro-2-(phenylthio)acetic acid (2) as one component, followed by removal of the phenylsulfanyl protecting group in the presence of tributyltin hydride and azobisisobutyronitrile. Keywords: difluoromethyl functionality; gem-difluoromethylene-containing acid; pseudopeptides; reductive

• cleavage; Ugi reaction; Introduction Fluorinated amino acids and pseudopeptides have increasingly attracted attention in recent years [1][2][3][4][5]. The selective incorporation of fluorine-containing groups, such as trifluoromethyl, difluoromethyl and difluoromethylene, into peptides or peptidomimetics

• isosteric and isopolar to the hydroxyl group and can behave as a hydrogen donor through hydrogen bonding [13]. However, to date, most fluorine-containing peptide modifications involve the introduction of trifluoromethyl or difluoromethylene into molecules [14][15][16][17][18]. Only a few examples have been

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• -difluoromethylene moiety has been reported to improve their biological activities. For example, a gem-difluoro-γ-lactam can inhibit γ-lactamase, which is responsible for bacterial resistance to γ-lactam antibiotics [2][3][4]. Additionally, α,α-difluoro lactams are precursors of some biologically active compounds [5

Synthesis of gem-difluoromethylenated analogues of boronolide

• Jing Lin,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2010, 6, No. 37, doi:10.3762/bjoc.6.37

• ]. Considering the similarity in size of fluorine and hydrogen atoms, the strong electron-withdrawing property of gem-difluoromethylene group (CF2) [19][20] and our continual efforts to prepare gem-difluoromethylenated analogues of natural products containing α,β-unsaturated-δ-lactone moiety [21][22][23][24], we

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• our knowledge, the effect of gem-difluoromethylene group on Pd-catalyzed cyclic allylic substitution has never been addressed so far. The regioselectivity was totally different from those of nonfluorinated substrates [18]. Unexpected and specific regioselectivity of Pd-catalytic asymmetric reactions

• electron-withdrawing property of the gem-difluoromethylene group. To further validate our hypothesis and the proposed model of DeShong et al., we decided to explore the crystal structure and 13C NMR of the corresponding Pd-π-allyl complex. In 2000, Bäckvall and co-workers investigated the X-ray structures

• to the strong electron-withdrawing property of neighboring gem-difluoromethylene group. 13C NMR spectroscopy of the trans-trans dimer 8 unambiguously demonstrated that C2 (t, δ = 73.2) experienced higher field than C4 (s, δ = 81.4), which was also ascribed to the strong electron-withdrawing property

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• enones can be used to introduce difluoromethylene moiety while Kumadaki and coworkers [21][22] have used bromodifluoroacetate with a copper catalyst to introduce the CF2 functionality. There also exist few reports on the 1,4-addition of monofluoromethylene moieties to α,β-unsaturated compounds [23][24