Synthesis of a derivative of α-D-Glcp(1->2)-D-Galf suitable for further glycosylation and of α-D-Glcp(1->2)-D-Gal, a disaccharide fragment obtained from varianose

• Carla Marino,
• Carlos Lima,
• Karina Mariño and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2012, 8, 2142–2148, doi:10.3762/bjoc.8.241

• α-D-Glcp unit in the HO-2 would hinder the proper diisoamylborane complexation. In order to relieve the conformational strain we prepared derivative 7 by deisopropylidenation followed by benzoylation of 5. Diisoamylborane reduction of 7 was more efficient and afforded 8 in 76% yield after 72 h of

• 100.4 and 99.3 for C-1 of the β and α-anomers, respectively. Derivative 8 is ready to be activated by the trichloroacetimidate method, for the synthesis of larger oligosaccharides. Conventional de-O-benzoylation and subsequent hydrogenolysis of 8 afforded disaccharide 1 in good yield (Scheme 1). The NMR

Enantioselective total synthesis of (R)-(−)-complanine

• Krystal A. D. Kamanos and
• Jonathan M. Withey

Beilstein J. Org. Chem. 2012, 8, 1695–1699, doi:10.3762/bjoc.8.192

• ). Although a number of acyloxylations have been reported, the direct catalytic asymmetric acyloxylation of aldehydes has only been recently realized [6][7]. Thus, the asymmetric benzoylation of aldehydes, according to the method of Tomkinson [7], was attempted. Utilizing benzoyl peroxide in the presence of

• MacMillan imidazolidinone (5R)-2,2,3-trimethyl-5-benzyl-4-imidazolidinone [8] with 4-nitrobenzoic acid as cocatalyst, all efforts to effect benzoylation of 3, yielding 5, were unsuccessful, and this route was ultimately abandoned as attention turned to more conventional α-oxygenation strategies and a

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• after benzoylation. Subsequent treatment of 11 with a second amount of Zn and LiCl (1.4 equiv) provides a new intermediate zinc reagent within 10 min, which after allylation provides the 2,5-disubstituted thiophene 12 in 87% yield (Scheme 3) [6]. The insertion reaction proceeds best with aryl and

• ketone are readily tolerated. Thus, the Boc-substituted benzophenone 130 reacts with TMP2Mg·2LiCl (1.1 equiv, −20 °C, 4 h) providing the expected aryl magnesium amide 131, which after a copper-mediated benzoylation leads to the 1,2,3-trisubstituted diketone 132 in 72% yield. This reagent allows a smooth

Synthesis of glycoconjugate fragments of mycobacterial phosphatidylinositol mannosides and lipomannan

• Benjamin Cao,
• Jonathan M. White and
• Spencer J. Williams

Beilstein J. Org. Chem. 2011, 7, 369–377, doi:10.3762/bjoc.7.47

• Glycosidation of 8-azidooctan-1-ol (Supporting Information File 2) using glycosyl bromide 11 [36] in the presence of AgOTf, and debenzoylation of the crude product gave 12 in 81% yield over 2 steps (Scheme 2). Regioselective silylation of the primary alcohol of 12 with TPSCl followed by benzoylation of the

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• oxidation [45] of the ketone followed by reduction with NaBH4, afforded dihydroxy camphor derivative 67. Periodic acid cleavage of the resulting vicinal diol and NaBH4 reduction in situ gave diol 68. Selective benzoylation of the less hindered alcohol and PCC oxidation led to compound 70. Six derivatives of