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

• the terminal position of the double bond due to steric effects. On the basis of the above mentioned results, a proposed mechanism for the formation of 5a–h is outlined in Scheme 1. Trialkylphosphine catalysed Morita-Baylis-Hillman reaction is well studied by a number of groups [37][38][39]. Addition

Solvent- controlled regioselective protection of allyl- 4,6-benzylidene glucopyranosides

• Kerry Ann Ness and
• Marie E. Migaud

Beilstein J. Org. Chem. 2007, 3, No. 26, doi:10.1186/1860-5397-3-26

• allyl ether at the C1 position of the glucoside. It can be postulated that in THF, regioselectivity depends on the relative acidity of the secondary hydroxyl groups and the nucleophilicity of the resulting alkoxide. The acidity is modulated by intramolecular H-bonds while steric effects control the

Synthesis of 2,6-trans- disubstituted 5,6-dihydropyrans from (Z)-1,5-syn-endiols

• Eric M. Flamme and
• William R. Roush

Beilstein J. Org. Chem. 2005, 1, No. 7, doi:10.1186/1860-5397-1-7

• identical, steric effects on the activation of the two hydroxyl groups are eliminated. Therefore, the enantioselectivity of the ring closing step will depend only on the relative rates of the competing cyclization processes leading to 3a and ent-3a. Initial attempts at cyclization of 2a using Ph3P and

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• (OsO4, TMEDA, CH2Cl2) conditions allow complementary diastereoselective functionalisation of the alkene of the (2R*,3R*) diastereoisomer. However, in the presence of a 6-substituent, the reaction is largely controlled by steric effects with both reagents. The most synthetically useful protocols were