The Influence of the 2-Alkoxy Group and of C-5 Substituents on the Direction of Reductive Cleavage of 2-Alkoxytetrahydrofurans by AlH<sub>2</sub>Cl in Ether Solution
作者:P. C. Loewen、Miss L. P. Makhubu、R. K. Brown
DOI:10.1139/v72-238
日期:1972.5.15
ring C—O bond cleavage. However, substituents at C-5 of 2-methoxytetrahydrofuran exert a strong effect on the ratio of ring to exo C—O bond cleavage. Thus, alkyl (electron donor) groups at C-5 promote an increase in the amount of exo cleavage, the proportion increasing from 62.5 to 100% as the C-5 alkyl group is changed from CH3 to t-C4H9. In contrast, electron withdrawing substituents, CH3OCH2— and
The reaction of silacyclobutane with benzaldehyde in the presence of a catalytic amount of potassium t-butoxide gave six-membered cyclic silyl ether. Meanwhile, treatment of a mixture of silacyclobutane and epoxide with lithium diisopropylamide provided silacyclopentane derivative.
作者:Robert-André F. Rarig、Matthew Scheideman、Edwin Vedejs
DOI:10.1021/ja800402g
日期:2008.7.1
Metal-free homoallylic oxygen-directed intramolecular hydroboration is reported. Regioselectivities from 20:1 to 82:1 favoring the 1,3-dioxy-substituted products have been achieved using Me2S center dot BH3/TfOH followed by standard oxidative workup. Branching at the C5 position improves regioselectivity.
Silylmethyl radical cyclization: new stereoselective method for 1,3-diol synthesis from allylic alcohols