Novel cleavage of (E)-allyl vic-diols to aldehydes using the 2nd-generation Grubbs catalyst
摘要:
Secondary (E)-allyl vic-diol cleavage in the presence of the 2nd-generation Grubbs catalyst has been developed. The position of a vic-diol adjacent to C=C plays a crucial role in the cleavage reaction compared to an alkyl vic-diol based on a model compound. (C) 2008 Elsevier Ltd. All rights reserved.
Highly diastereoselective aldol reactions of α-bromo ketones with several aldehydes were successfully carried out by using a combination of titanium(II) chloride and copper or sodium iodide in dichloromethane-pivalonitrile at low temperature. Similarly, Reformatskyreactions of α-bromo thioester with aliphatic aldehydes proceeded to afford β-hydroxy thioesters in good yields under mild conditions.
通过在低温下在二氯甲烷-新戊腈中使用氯化钛 (II) 和碘化铜或碘化钠的组合,成功地进行了 α-溴酮与几种醛的高度非对映选择性羟醛反应。类似地,α-溴硫酯与脂肪醛的 Reformatsky 反应在温和条件下以良好的产率得到 β-羟基硫酯。
Simple and expeditious pinacol coupling of non usual α,β-unsaturated carbonyl compounds in water
作者:Muriel Billamboz、Nicolas Sotto、Carole Chevrin-Villette、Christophe Len
DOI:10.1039/c5ra03870g
日期:——
Using zinc (0) in a 5% v AcOH aqueous solution allowed the efficient pinacolcoupling of aliphatic or aromatic unusual, α,β-unsaturated carbonylcompounds such as citral A in good to excellent yields (56–99%). It can also be successfully applied to acetophenone.
Diastereoselective Pinacol Coupling Reaction of Aliphatic and Aromatic Aldehydes Promoted by Low Valent Titanium Iodide in situ Formed by Titanium(IV) Iodide and Copper
The pinacol coupling reaction of aromatic and aliphatic aldehydes including pivalaldehyde with low valent titanium iodide, in situ formed from titanium iodide(IV) and copper, proceeded smoothly in a mixed solvent of dichloromethane and pivalonitrile to give the corresponding 1,2-diols in good to high yields and dl-selectivities.
Highly diastereoselective aldol reaction of α-bromo ketones with aliphaticaldehydes was successfully carried out by using titanium(II) chloride and copper in dichloromethane at low temperature. Similarly, Reformatsky-type reaction of α-bromo thioester with aliphaticaldehydes was promoted under mild conditions to afford β-hydroxy thioesters in good to moderate yields.
The invention concerns delayed release flavourant compositions.
In particular, these compositions are selected from the group consisting of
a) smoking compositions and
b) foodstuffs, in particular
b1) bakeable foodstuffs and
b2) microwaveable foodstuffs
containing flavour-release additives, namely 1,2―diols of the formula
wherein R1 is one of the radicals
where
R2 isH, lower alkyl
R3, R4 areH, lower alkyl, lower alkoxy, hydroxy, or R3 + R4 together are methylenedioxy,
R5 islower alkyl
and the broken lines represent in the ring one additional bond
and in the side chain an optional bond.