104174-74-5Relevant academic research and scientific papers
Facile and highly diastereoselective synthesis of syn- and cis-1,2-diol derivatives from protected α-hydroxy ketones
Jahn, Emanuela,Smr?ek, Jakub,Pohl, Radek,Císa?ová, Ivana,Jones, Peter G.,Jahn, Ullrich
, p. 7785 - 7798 (2015/12/31)
An efficient method for the synthesis of monoprotected syn- or cis-1,2-diol derivatives by reduction of easily accessible α-(2,2,6,6-tetramethylpiperidinyloxy) ketones is reported. The α-(tetramethylpiperidinyloxy) group as the stereodirecting group induces in unhindered acyclic or cyclic ketones complete syn- or cis-diastereoselectivity, respectively, with L-Selectride. For more hindered derivatives, where L-Selectride becomes unreactive, LiAlH4 proved effective, essentially showing the same high selectivity. The diastereoselectivity of the reduction can be rationalized for acyclic ketones by the Felkin-Anh model, whereas for cyclic substrates, attack from the face opposite to the tetramethylpiperidinyloxy group predictably prevails with high selectivity regardless of the substitution pattern. The liberation of free diols was achieved by reductive N-O bond cleavage of the alkoxyamine unit. Monoprotected syn- and cis-1,2-diols were synthesized by reduction of ketones bearing the stereodirecting α-(2,2,6,6-tetramethylpiperidinyloxy) group. The latter induces syn- or cis-selectivity in unhindered acyclic or cyclic ketones with L-Selectride, whereas the smaller LiAlH4 induced excellent diastereoselectivity with hindered ketones. Free 1,2-diols were liberated by reductive N-O bond cleavage.
The effect of protecting groups on tin-lithium exchange in α- alkoxyalkyltrimethylstannanes
Chong, J. Michael,Nielsen, Nathan
, p. 9617 - 9620 (2007/10/03)
MOM-protected α-hydroxytrimethylstannanes do not undergo tin-lithium exchange cleanly as their tributyl-counterparts do. Other protecting groups (e.g. N,N-diethylcarbamate) allow for clean transmetalation to occur presumably due to the formation of a more
Cyclocondensation of oxalyl chloride with 1,2-glycols
Iida,Itaya
, p. 10511 - 10530 (2007/10/02)
Oxalyl chloride reacts with a wide range of acyclic 1,2-glycols 1 in the presence of triethylamine to produce 1,3-dioxolan-2-ones 3 together with 1,4-dioxane-2,3-diones 2. Ethylene glycol (1d), monosubstituted ethylene glycols 1e, j-l, and erythro-1,2-disubstituted ethylene glycols 1f, m, o provide the cyclic carbonates 3 as the minor products, while the threo-compounds 1g, i, n, p, q and pinacol (1h) afford 3 as the main products. The formation of 3 may be rationalized in terms of stereoelectronically controlled cleavage of the conjugate base 17- of the tetrahedral intermediates. The rate of the conformational change of 17- into 18- and the equilibrium constant between these conformers are proposed to be the major factors affecting the reaction pattern.
