Synthesis of chiral cyclohexanes and carbasugars by 6-exo-dig radical cyclisation reactions

• Rajeev K. Shrivastava,
• Elise Maudru,
• Gurdial Singh,
• Richard H. Wightman and
• Keith M. Morgan

Beilstein J. Org. Chem. 2008, 4, No. 43, doi:10.3762/bjoc.4.43

• juncture we were able to separate the diastereoisomers, 3a (anti) and 3b (syn), by flash column chromatography on silica gel. Alternatively the syn isomer 3b could be prepared almost exclusively using D-ribonolactone as the starting material [23]. Desilylation of 3a was effective with TBAF in THF and

• 96% and 91% yields, respectively. These compounds were identical to those obtained from 2c after the diastereoisomers had been subjected to protection as MOM ethers on treatment with MOM chloride to give 5a and 5b followed by desilylation, the anti:syn ratio being 2.3:1. The syn-product was

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• unsuccessful, apparently because the silyl ether failed to survive the reaction conditions. Inelegant though it was, we were forced at this stage to change protecting groups on the alcohol. Fortunately, the drop in yield was not too serious when desilylation of 34 with aqueous hydrofluoric acid to give the

Investigation of acetyl migrations in furanosides

• O. P. Chevallier and
• M. E. Migaud

Beilstein J. Org. Chem. 2006, 2, No. 14, doi:10.1186/1860-5397-2-14

• O. P. Chevallier M. E. Migaud School of Chemistry and Chemical Engineering, Queen's University, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, Northern Ireland, UK 10.1186/1860-5397-2-14 Abstract Standard reaction conditions for the desilylation of acetylated furanoside (riboside

• ribosides, acyl migration could be prevented when desilylation was catalysed by cerium ammonium nitrate. Introduction Over the years, a number of methods aimed at achieving chemoselective acylation of carbohydrates have been developed.[1][2][3] In addition to the challenges encountered in the selective

• experiments were sufficiently clear to allow accurate compound identification. No isomerisation was detected for any of the isolated compounds when stored in an organic solvent such as hexane, ethyl acetate or CDCl3 for up to 12 hrs. The chemical shifts of the 1H- and 13C-NMR of the desilylation products for

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• failed. Fortunately, use of LiHMDS was successful albeit accompanied by the unexpected loss of Boc group. Similar strategies using either the free diol or the corresponding acetonide were not successful leading to extensive decomposition. Following TBAF promoted desilylation, peracylation and reduction

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• silylketenes with reactive ylides involves deprotonation by the basic reagent to generate ynolate anions. Clearly, since such a pathway cannot operate with the substituted ketenes used here other mechanisms are at play, which may include nucleophilic desilylation or ketene oligomerisation initiated by