TīmeklisFelkin-Anh is based on a reaction in which the metal and nucleophilic group both interact with the ends of the carbonyl bond simultaneously. They come together so that the orbitals of the newly formed sp3 carbon do not eclipse with the already existing bonds, or so that the largest substituent on the neighboring carbon is anti to the … Tīmeklis2024. gada 15. jūn. · An improvement over Felkin's model was the Felkin-Nguyen (Felkin-Anh) model, which suggested that the nucleophile would attack the sp 2 center of the carbonyl at 95 0 to 105 0 angle relative to the carbonyl bond axis, favoring an attack from the least hindered direction (Figure 1.2.6). This differed from the earlier …

フェルキン-アーンのモデル - Wikipedia

TīmeklisWith this change in mind, the Felkin-Ahn type addition now proceeds as before. What that tends to mean in most cases (not all), is that the ‘medium’ group ends up being part of the product’s main chain, and most often this means that the anti- diastereomer is the one formed. O H X ππππ* H σσσσ* O NMe2 1) BuLi, Et2O 2) H2O OH NMe2 ... TīmeklisNormal Felkin-Ahn model (No α-heteroatoms) 2. Electronegative heteroatom perpendicular 3. Electonegative heteroatom chelated and in the plane of the carbonyl … luther hall south daytona

Cram則 - Chem-Station

Tīmeklis2010. gada 8. aug. · Felkin-Anhモデルとは立体選択性が逆になるよう解釈される。 すなわち、金属が配位性官能基Dおよびカルボニル酸素とキレートした配座が優先と … Several models exist to describe chiral induction at carbonyl carbons during nucleophilic additions. These models are based on a combination of steric and electronic considerations and are often in conflict with each other. Models have been devised by Cram (1952), Cornforth (1959), Felkin (1969) and others. The Cram's rule of asymmetric induction developed by Donald J. Cram in 195… Tīmeklis2024. gada 22. apr. · ケトンの還元とfelkin anhモデルについて質問です。 この反応は、 ①NaBH4を用いると選択性はほとんどない(わずかにanti優先) ②L-selectrideを用いるとsynアルコール異性体が優先 するらしいのですが、理由が分かりません。 どちらもヒドリド還元剤なので、違い ... jbl vs beats wireless workout earbuds