68882-71-3Relevant articles and documents
Jatrophone Analogues: Synthesis of cis- and trans-Normethyljatropholactones
Smith, Amos B.,Malamas, Michael S.
, p. 3442 - 3447 (1982)
This, a full account, discloses an efficient, convergent synthesis of two novel analogues of the macrocyclic antitumor diterpene jatrophone (1).We term these analogues cis- and trans-normethyljatropholactone (2 and 3, respectively).Our approach in each case begins with the bis(trimethylsilyloxy) ketone 7 and the requisite acetylenic or trans ester-aldehyde, 8 or 12a.Application of our previously developed 3(2H)-furanone synthetic protocol consisting of aldol condensation of the lithium enolate derived from 7 with the respective ester-aldehydes 8 or 12a, followed byoxidation (Collins reagent) and acid-catalyzed cyclization-dehydration, affords spirofuranone 6c and 14c, respectively, in 52percent and 45percent overall yields.Sodium borohydride reduction, ester hydrolysis, and closure of the macrolide by employing the conditions of Mukaiyama (i.e., 1-methyl-2-chloropyridinium iodide-/Et3N/CH3CN) in the case of spirofuranone 14a leads directly to trans-normethyljatropholactone (3), while completion of cis-normethyljatropholactone (2) requires first semihydrogenation; the latter was accomplished by employing PdSO4 in pyridine as the catalyst.The overall yields of 2 and 3, based on 7, were 23percent and 21percent, respectively.
Late-Stage Intermolecular Allylic C-H Amination
Clark, Joseph R.,Dixon, Charlie F.,Feng, Kaibo,Han, Wei,Ide, Takafumi,Koch, Vanessa,Teng, Dawei,Wendell, Chloe I.,White, M. Christina
supporting information, p. 14969 - 14975 (2021/10/01)
Allylic amination enables late-stage functionalization of natural products where allylic C-H bonds are abundant and introduction of nitrogen may alter biological profiles. Despite advances, intermolecular allylic amination remains a challenging problem due to reactivity and selectivity issues that often mandate excess substrate, furnish product mixtures, and render important classes of olefins (for example, functionalized cyclic) not viable substrates. Here we report that a sustainable manganese perchlorophthalocyanine catalyst, [MnIII(ClPc)], achieves selective, preparative intermolecular allylic C-H amination of 32 cyclic and linear compounds, including ones housing basic amines and competing sites for allylic, ethereal, and benzylic amination. Mechanistic studies support that the high selectivity of [MnIII(ClPc)] may be attributed to its electrophilic, bulky nature and stepwise amination mechanism. Late-stage amination is demonstrated on five distinct classes of natural products, generally with >20:1 site-, regio-, and diastereoselectivity.
Novel synthesis method of hepatitis B treating medicine entecavir
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Paragraph 0019; 0035-0037, (2019/01/08)
The invention discloses a novel method for synthesizing entecavir. The novel method takes a compound with a known formula 9 as a starting raw material, and a target molecule is synthesized through a series of reactions including a Morita-Baylis-Hillman reaction, a Sharpless asymmetric epoxidation reaction, TBSCl hydroxyl protection, an opening epoxidation reaction, TBSCl hydroxyl protection, a step of reducing carbonyl into double bonds, SeO2 one-step oxidization double-bond alpha-site H ketone formation reaction, a step of reducing ketone into hydroxyl through lithium triethylborohydride andthe like. The design of a whole route is unique and novel; a reaction process has mild reaction conditions and a rapid speed; side reactions are relatively few and the operation is simple and convenient; conventional chemical reagents are utilized in the route; the raw material is cheap and easy to obtain and the synthesis cost can be greatly reduced.
