![](/client/images/blank.gif)
Eylem Seç
![Approaches towards a total synthesis of the phomactins için kapak resmi Approaches towards a total synthesis of the phomactins için kapak resmi](/client/assets/d79c3e4af2b6d196/ctx/images/no_image.png)
Approaches towards a total synthesis of the phomactins
Başlık:
Approaches towards a total synthesis of the phomactins
Yazar:
McGowan, Graham, author.
ISBN:
9780355978100
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (229 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
Within this thesis is described a convergent approach towards a synthesis of the phomactins, novel platelet activating factor antagonists. The syntheses of the C1-C20 and C2-C9 phomactin fragments are described. The former is obtained in 33% yield over seven steps from the Birch reduction of ortho-toluic acid. The latter fragment is available form propargyl alcohol in 37% overall yield. The union of these fragments is achieved by a modified Williamson etherification. Subsequent transformations furnish the macrocyclic ether 203 in seven steps via sulfone 198. The attempted [2,3]-Wittig rearrangement of 203 is described. The [2,3]-Wittig rearrangement of acyclic sulfone 198 is also discussed. Treatment of this compound with n-butyllithium leads to an 82: 18 mixture of diastereoisomeric alcohols 205 alpha and 205 beta; the stereoselectivity of this rearrangement is considered. Protection and functional group interconversion of these compounds gave the macrocyclic carbinol, (1RS, 2RS, 7E, 11SR,. 12RS, 14SR)-8,11,12-trimethyl-15- methylene-14-(2'-trimethylsilanyl-ethoxymethoxy)-bicyclo[9.3.1]penatdec-7-en-3-yn-2-ol 212. This compound possesses all but one of the carbons of the phomactin skeleton. The introduction of the final carbon C16 was investigated. Oxidation of alcohols 205 alpha and 205 beta gave a single alkynone, (1'SR, 3'SR, 4'RS, 6'SR, 6E)-1-[benzenesulfonylmethyl-3',4'-dimethyl-2'-methyIene- 6'-(2''-trimethylsilanyl-ethoxymethoxy)-cyclohexyl]-8-(tert-butyl-diphenyl- silanyloxy)-7-methyl-oct-6-en-2-yn-1-one 238. Addition of benzenethiol to this compound allowed the introduction of the C16 methyl group of the phomactins in a stereoselective fashion. Reduction and protection the E-enone 240 allowed cyclisation to afford the advanced intermediate alcohol (IRS, 2SR, 3E, 6E, 11SR,12RS, 14SR)-4,8,11,12-tetramethyl-15- methylene-14-(2-trimethylsilanyl-ethoxymethoxy)-bicyclo[9.3.1]pentadec-3,7-dien-2-ol 250.
Notlar:
School code: 1543
Konu Başlığı:
Tüzel Kişi Ek Girişi:
Mevcut:*
Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(683846.1) | 683846-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
On Order
Liste seç
Bunu varsayılan liste yap.
Öğeler başarıyla eklendi
Öğeler eklenirken hata oldu. Lütfen tekrar deneyiniz.
:
Select An Item
Data usage warning: You will receive one text message for each title you selected.
Standard text messaging rates apply.