Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• ) methoxide (102) underwent Ga‒O/B‒C exchange with allyl-Bpin 103 to give MeOBpin and an allylic gallium(I) species 104, which reacted with the oxocarbenium 103 to give the allylic ether 105 and regenerate the GaI catalyst 99 (Scheme 25). Using allenylBpin, the selective propargylation of acetals was also

Novel carbocationic rearrangements of 1-styrylpropargyl alcohols

• Christine Basmadjian,
• Fan Zhang and
• Laurent Désaubry

Beilstein J. Org. Chem. 2015, 11, 1017–1022, doi:10.3762/bjoc.11.114

• be envisioned that this compound results from the rearrangement of an allene oxide (Scheme 5). Interestingly the dipropargylic alcohol 9 afforded the rearranged allylic ether 20 as the only isolated product (entry 6, Table 1). In order to improve the yields of these reactions and gain insight in the

• article, we demonstrate the delicate balance among several mechanistic pathways by a minor change of substrate in acid-catalyzed rearrangements of 1-styrylpropargyl alcohols. Indeed, these compounds may generate a furan (18), an enone (19), an allylic ether or even a naphthalenone (17). The formation of

C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog

• Sebastian Rabe,
• Johann Moschner,
• Marina Bantzi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 1564–1569, doi:10.3762/bjoc.10.161

• part of our continuing work on acid-stable cyclopamine analogs [12][13] we have now focused on the role of the allylic ether oxygen in the acid-mediated E-ring cleavage and decomposition of cyclopamine [24]. We envisioned that its replacement by a methylene group would create an acid-stable cyclopamine

De novo synthesis of D- and L-fucosamine containing disaccharides

• Daniele Leonori and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 332–341, doi:10.3762/bjoc.9.38

• blocks Our retrosynthetic analysis of D-fucosamine envisioned the installation of the syn-1,2-diol unit by osmium-catalysed dihydroxylation of allylic ether A. It was anticipated that the conformation adopted by the molecule would allow for the formation of the required anti relationship between C3 and

A comparative study of the Au-catalyzed cyclization of hydroxy-substituted allylic alcohols and ethers

• Berenger Biannic,
• Thomas Ghebreghiorgis and
• Aaron Aponick

Beilstein J. Org. Chem. 2011, 7, 802–807, doi:10.3762/bjoc.7.91

• corresponding ethers. Additionally, it is reported that Reaxa QuadraPureTM MPA is an efficient scavenging reagent that halts the reaction progress. Keywords: allylic alcohol; allylic ether; Au-catalyzed; SN2'; tetrahydropyran; Introduction Saturated oxygen heterocycles are found in a wide variety of

• usually very poor leaving groups, but function extremely well in the present system, it seemed likely that a fairly robust group could perform satisfactorily here. Additionally, calculations suggest that in intermolecular hydroalkoxylation reactions of allenes the kinetic allylic ether products are

• such as benzoyl (16) were unsuitable. This may provide a basis for chemoselective transformations, as allyl esters are readily ionized by Pd0 complexes and the resulting π-allylpalladium species are alkylated by a variety of nucleophiles [27][28]. Finally, 1° allylic and 2° allylic ether substrates

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• . With the optically pure chiral alcohol (R)-PhMeCHCH2OH as a nucleophile, the reaction was not diastereoselective and led to the tertiary allylic ether 9k (65%) as a 1:1 mixture of diastereomers. An unprotected primary and tertiary 1,3-diol reacted chemoselectively with the primary alcohol to furnish

• ethers 11a and 11’a was obtained under the previously used reaction conditions. By lowering the temperature to 10 °C and increasing the quantity of n-BuOH (15 equiv), the tertiary allylic ether 11a (65%) was obtained regioselectively (11a/11’a > 99:1). Curiously, a complete switch of the regioselectivity

• took place when phenethyl alcohol was employed as a nucleophile, since in this case the primary allylic ether 11’b (65%) was obtained (11b/11’b > 1:99) (Scheme 6) [19]. The formation of the tert-allylic ethers 9 can be explained by the regioselective attack of the alcohol at C3 on the organogold