Oxirane ring-opening with alcohol catalyzed by organotin phosphate condensates. Complete inversion at tertiary and benzylic centers

C2-Symmetric Copper(II) Complexes as Chiral Lewis Acids. Catalytic Enantioselective Carbonyl−Ene Reactions with Glyoxylate and Pyruvate Esters

“…However, with complex [Cu(( S,S )- t -Bu-box)(SbF 6 ) 2 ( 2a ), 1-hexene is a viable substrate in this reaction affording ethyl ( S )-2-hydroxy-4-octenoate ( 21 ) in 98% ee with excellent ( E ) olefin selectivity (96:4) (eq 10). The absolute configuration of the ene product 10 was determined by sequential hydrogenation and reduction to afford (2 S )-octane-1,2-diol for which the spectral data and optical rotation were identical to that reported in the literature …”

“…The absolute configuration of the ene product 10 was determined by sequential hydrogenation and reduction to afford (2S)-octane-1,2-diol for which the spectral data and optical rotation were identical to that reported in the literature. 20 To demonstrate the preparative utility of this methodology, the reaction of ethyl glyoxylate with methylene cyclohexane was conducted on a 25-mmol scale employing 0.2 mol % (43 mg) of the Cu(II)-box catalyst 4 to generate the desired adduct 6 (4.3 g) in high yield and enantioselectivity (86%, 97% ee).…”

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

“…The alcoholysis of epoxides to form β‐hydroxy ethers is an important intermediate step in the synthesis of many small molecules and is normally catalyzed by Brønsted or Lewis acids . Heterogeneous acidic catalysts that have been successfully employed for this purpose include sulfonated polymers (Amberlyst‐15 and Nafion‐H), neutral alumina, mesoporous aluminosilicate, organotin phosphate condensates (OPCs), and Fe 3+ ‐montmorillonite, but it is unlikely that they could achieve sufficient interaction with the pendant functionalities of polymers to efficiently promote functionalization. Soluble compounds or complexes of main group metals, transition metals, and lanthanides are well‐known for their Lewis acidity and have been investigated specifically for their ability to catalyze the alcoholysis of epoxides.…”

“…9 Heterogeneous acidic catalysts that have been successfully employed for this purpose include sulfonated polymers (Amberlyst-15 and Nafion-H), 10,11 Additional Supporting Information may be found in the online version of this article. neutral alumina, [12][13][14] mesoporous aluminosilicate, [15][16][17] organotin phosphate condensates (OPCs), [18][19][20] and Fe 31 -montmorillonite, 21 but it is unlikely that they could achieve sufficient interaction with the pendant functionalities of polymers to efficiently promote functionalization. Soluble compounds or complexes of main group metals, [22][23][24][25][26][27][28][29][30][31] transition metals, 22,25,27,29,[32][33][34][35][36][37][38][39][40][41][42][43][44][45] and lanthanides 22,27,[46][47][48]…”

Amidines in Organic Synthesis

“…DBU (1) was used as a base in the dehydrochlorination/ring closure of chiral chlorohydrins with high retention of optical purity [60]. N-Acyl-b-hydroxy-4-phenyloxazolidinethiones are rapidly converted into the corresponding ethyl thioesters in high yields by treatment with ethanethiol (EtSH) in the presence of a catalytic DBU (1) [61] (Scheme 3.37).…”