Sequential One-Pot Isomerization-Wittig Olefination-Hydrogenation

Abstract

Primary allylic alcohols are isomerized to aldehydes in the presence of Pd(OH) 2 and homologated to a,b-unsaturated carbonyl derivatives in one-pot by addition of stabilized Wittig ylides in a sequential fashion. When the reaction was prolonged by addition of more catalyst, a hydrogenation step succeeds the Wittig olefination. In addition, sequential isomerization-Wittig olefination-oxaMichael addition reaction provides tetrahydropyran with high diastereoselectivity.

Oxidative Deprotection ofp-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis

“…7-((4-Methoxybenzyl)oxy)heptan-2-one (1z). 39 Following the general procedure using 9% ethyl acetate in hexanes as eluant, 1z was obtained as a colorless liquid; 1 H NMR (300 MHz, CDCl 3 ) δ 7.28−7.22 (m, 2H), 6.90−6.84 (m, 2H), 4.42 (s, 2H), 3.80 (s, 3H), 3.43 (t, J = 6.5 Hz, 2H), 2.42 (t, J = 7.4 Hz, 2H), 2.13 (s, J = 0.5 Hz, 3H), 1.65−1.52 (m, 4H), 1.42−1.29 (m, 2H); 13 C NMR (75 MHz, CDCl 3 ) δ 209.3, 159.2, 130.8, 129.4, 113.9, 72.7, 70.0, 55.4, 43.8, 30.0, 29.7, 25.9, 23.7.…”

Molecular iodine-catalyzed multicomponent reactions: an efficient catalyst for organic synthesis

“…Sakurai-Prins-Ritter reaction, 72 which involved an aromatic aldehyde, allyltrimethylsilane and acetonitrile (without acetyl chloride), afforded the products of symmetrical 4-amido tetrahydropyrans 77 in satisfactory yields within a short time (Scheme 31). The reactions were also successful with aliphatic aldehydes and other nitriles (such as benzonitrile, 4-methyl benzonitrile, and isobutyronitrile) to produce the corresponding 4-amido tetrahydropyrans 78 in good yields.…”

6.07 Ritter-Type Reactions

“…For example, the conversion in equation 144 may be carried out using excess BF 3 ·Et 2 O, 239 or catalytic amounts of either bismuth triflate 240 or molecular iodine. 241 Use of a 1,3-dioxane derivative as an aldehyde equivalent permits the incorporation of significant stereochemistry, thereby leading to excellent product diastereoselectivity (Scheme 67). The method is applicable to a wide range of nitriles, including functionalized examples.…”