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Search for "1,2-addition" in Full Text gives 60 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of novel derivatives of 5-hydroxymethylcytosine and 5-formylcytosine as tools for epigenetics
Beilstein J. Org. Chem. 2014, 10, 7–11, doi:10.3762/bjoc.10.2
- the aldehyde group (1,2-addition) were not observed. The formation of compounds 8a–d can be explained assuming a Michael-type reaction of aldehyde 5 with organometallic reagents, subsequent isomerisation of the double bond followed by removal of one TCBoc group during the reaction and work-up as shown
Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products
Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300
- ]. Chisholm has been looking for milder catalytic metal-alkyne nucleophiles for carbonyl 1,2-addition reactions, which wouldn’t enolize the labile α-protons next to a carbonyl group (Scheme 17) [71]. They found that a Rh(I)-catalyst with a monodentate electron rich phosphine ligand 42 formed a nucleophilic
Regioselective 1,4-trifluoromethylation of α,β-unsaturated ketones via a S-(trifluoromethyl)diphenylsulfonium salts/copper system
Beilstein J. Org. Chem. 2013, 9, 2189–2193, doi:10.3762/bjoc.9.257
- Michael addition reaction, even in a racemic, non-stereoselective fashion [1][2][3][4][5]. The nucleophilic trifluoromethylation to conjugated alkenes essentially occurs solely via a 1,2-addition [1][2][3][4][5][6][7][8][9][10][11], not a 1,4-addition (Scheme 1), with the exception of non-general examples
Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis
Beilstein J. Org. Chem. 2013, 9, 1170–1178, doi:10.3762/bjoc.9.131
- of N-1,4-addition and C-1,2-addition/β-elimination [16][17], effectively leading to a variety of nitrogen heterocyclic motifs, such as 3, which are prevalent among alkaloids (Scheme 1) [16][26][27][28][29][30][31][32]. However, there was a significant deficiency in this annulation: the inability to
Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization
Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177
- related bonds, their potential utility lies in the fact that they can also react with unpolarized H–H and C–H bonds (including those of methane). The result is a 1,2-addition of X–H across the M═E bond to give a M(X)(EH) species, which may in some cases react further. A prominent example was reported by
- the types of reactivity discussed thus far, there are several distinct routes to the functionalization of C–H (or E–H) bonds using metal–ligand multiply bonded FLPs. If C–H activation is effected by 1,2-addition across a M═E bond, then reductive elimination could result in a net C–H insertion of
- a transformation has not been realized with the early metal complexes that are most reactive toward C–H bonds, probably because reductive elimination is strongly disfavored relative to the 1,2-elimination of alkane. Another possibility would be an initial 1,2-addition of a C–H bond across M═E
Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions
Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168
- protocol starts from alkenes, which are transformed by a 1,2-addition of iodine azide and then to the corresponding vinyl azides. Furthermore, for the first time we present the copper-mediated Huisgen-type “click” cycloaddition of vinyl azides with alkynes to yield vinyl triazoles under inductive-heating
When gold can do what iodine cannot do: A critical comparison
Beilstein J. Org. Chem. 2011, 7, 847–859, doi:10.3762/bjoc.7.97
- developed a 5-endo approach to the iodocarbocyclization between ß-keto esters and non-terminal alkynes (Scheme 13b) [108]. Initially, 1,2-addition of iodine to alkynes such as 45 proved problematic, which was resolved by decreasing the molarity of the iodine in CH2Cl2 from 0.3 M to 0.05 M. This favored the
The arene–alkene photocycloaddition
Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61
- dependent on the electronic properties of the two reaction partners [14]. He reported that 1,2-addition usually prevails when a high degree of charge transfer is involved in the exciplex (ΔGET below 0.5 eV). A substituent at position 1 stabilizes the charge which develops on the aromatic ring, and therefore
A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions
Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31
- observed, a compound type which is produced (derivative 6) when benzanthrone was treated with phenyl lithium [3]. The yield of 4 was not improved by addition of a copper(I) salt in catalytic amounts [4]. This procedure should have favoured the ratio of a 1,4- to a 1,2-addition product [5]. The enol 4 is
Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds
Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17
- " nucleophiles that readily undergo 1,2-addition with Michael type acceptors instead of 1,4-addition [14][15][16]. Different strategies have been employed to achieve 1,4-addition, which is still percieved to be a challenge. For instance, Yamamoto [17] and Röschenthaler [18][19] have made use of bulky aluminum
- Lewis acids to protect the carbonyl of Michael acceptors and thus sucessfully transferred the trifluoromethyl anion generated from the "Ruppert-Prakash reagent" (TMS-CF3) in a 1,4-manner rather than the favored 1,2-addition. Portella et al. [20] have shown that 1,4-addition of difluoroenoxysilanes to
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