Electrophilic additions to nonactivated C=C bonds are one of the well-known classical reactions utilized by synthetic chemists as a starting point to construct useful complex organic molecules. This chapter covers a collection of electrophile-initiated domino transformations involving alkenes as the first reaction, followed by reaction with suitable nucleophiles in the succession and termination reactions under identical conditions. The discussion focuses on recent advances in catalysis, strategically designed alkenes, and new electrophilic reagents employed to improve reactivity and control of stereochemistry in the sequence of bond-forming steps.
Cyclopropane having alkane and alkene properties plays an important role in many reactions and its intermediates. There has been numerous researches done on the reactions of Donor-Acceptor cyclopropane (D-A cyclopropane) (Reisig & Zimmer, 2003), otherwise known as di-activated cyclopropane. However, only a little attention was focused on the chemistry of mono-activated cyclopropane. It is hypothesized that mono-activated cyclopropane can also achieve the same results as that of a di-activated one. This can be actualized by employing a highly ring strain hydrocarbon, and a mono-substituent. With the development of methodology for the mono-activated cyclopropane, simplification to the synthetic steps of complex organic structures can be made. Until now, it can be concluded that SnCl 4 seemed to be a suitable catalyst for this reaction. A good reactive rigid carbonyl cyclopropane may be bicyclo[3.1.0]hexanone while 2,3-dihydropyran is not a good olefin (substrate). Although the development of this methodology is still at its infancy, successful advancement in this area of research will allow us to experiment with the concept on dynamic combinatorial chemistry.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The authors reported that CBS reduction of 2,2-disubstituted cycloalkan-1,3-diones or hindered 2,2-disubstituted cyclic ketones using catecholborane as reductant proceeds with greater selectivity than when PhNEt2 is added. After careful experiments, it is believed that the beneficial effect of this additive may be due to the ability of this amine to catalyze the conversion of a minor harmful impurity in catalyst preparations to the active catalyst.
Electrophilic additions to nonactivated C=C bonds are one of the well-known classical reactions utilized by synthetic chemists as a starting point to construct useful complex organic molecules. This chapter covers a collection of electrophile-initiated domino transformations involving alkenes as the first reaction, followed by reaction with suitable nucleophiles in the succession and termination reactions under identical conditions. The discussion focuses on recent advances in catalysis, strategically designed alkenes, and new electrophilic reagents employed to improve reactivity and control of stereochemistry in the sequence of bond-forming steps.
(1; R = Me) [17640-15-2] C3H3NO2 (MW 85.07) InChI = 1S/C3H3NO2/c1-6-3(5)2-4/h1H3 InChIKey = OBWFJXLKRAFEDI-UHFFFAOYSA-N (2; R = Et) [623-49-4] C4H5NO2 (MW 99.10) InChI = 1S/C4H5NO2/c1-2-7-4(6)3-5/h2H2,1H3 InChIKey = MSMGXWFHBSCQFB-UHFFFAOYSA-N (3; R = PhCH2) [5532-86-5] C9H7NO2 (MW 161.17) InChI = 1S/C9H7NO2/c10-6-9(11)12-7-8-4-2-1-3-5-8/h1-5H,7H2 InChIKey = GDZIODIYBLTRRJ-UHFFFAOYSA-N (agent for the regioselective methoxycarbonylation of carbanions;1, 2 reacts with organocadmium reagents to form α-keto esters;3 may function as a dienophile,4 dipolarophile,5 or radical cyanating agent6) Physical Data: (1) mp 26 °C; bp 100–101 °C; d 1.072 g cm−3. (2) bp 115–116 °C; d 1.003 g cm−3. (3) bp 66–67 °C/0.6 mmHg; d 1.105 g cm−3. Solubility: sol all common organic solvents; dec by H2O, alcohols, amines. Form Supplied in: colorless liquid; methyl cyanoformate, as well as the ethyl and benzyl analogs, is available commercially. Preparative Methods: small quantities of cyanoformate esters (up to 30 g) may be conveniently prepared from alkyl chloroformates by procedures employing phase-transfer catalysis with either 18‐Crown‐67 or Tetra‐n‐butylammonium Bromide,8 but several workers have found the products to be unsatisfactory when prepared on a larger scale. Handling, Storage, and Precautions: store over 4 Å molecular sieves; highly toxic; flammable; use in a fume hood.
Elegant, effizient und enantiospezifisch gelingt die erste Totalsynthese des Quassinoids (−)-Samaderin Y (siehe Schema), das in vitro cytotoxisch wirkt und daher als Tumortherapeutikum in Betracht kommt. Ausgehend von (S)-(+)-Carvon war die Synthese nach 21 Stufen beendet.
Tamiflu (oseltamivir phosphate) is a potent neuramidase inhibitor which is used for the treatment of the avian H5N1 virus. Key steps in the 10-step asymmetric synthesis depicted include (a) an efficient asymmetric Diels-Alder reaction mediated by an enantiopure catalyst and (b) a stereoselective electrophilic addition of N-bromoacetamide to an alkene mediated by SnBr4.
Elegant, efficient, and enantiospecific describe the first total synthesis of the quassinoid (−)-samaderine Y (see scheme), which has been shown to display in vitro cytotoxicity and is of interest as a potential antitumor agent. Its synthesis has been accomplished from (S)-(+)-carvone in 21 steps. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z502763_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
Electrophilic additions to nonactivated C=C bonds are one of the well-known classical reactions utilized by synthetic chemists as a starting point to construct useful complex organic molecules. This chapter covers a collection of electrophile-initiated domino transformations involving alkenes as the first reaction, followed by reaction with suitable nucleophiles in the succession and termination reactions under identical conditions. The discussion focuses on recent advances in catalysis, strategically designed alkenes, and new electrophilic reagents employed to improve reactivity and control of stereochemistry in the sequence of bond-forming steps.
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