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[timur2312]

помогите кто-нибудь пожалуйста  перевести

 

Selective reduction of the nitro group in 8 presented another major challenge. Conditions such as Zn,¹ Zn/HC0₂NH₄, Zn/H₂NNH₂.HC0₂H,¹⁷ In,¹⁸ In/NH₄C1,¹⁹ Fe,²⁰ Fe-FeCl*²¹ Mg/H₂NNH₂-HC0₂H,²² and SnCl^ as well as Adam's and Lindlar’s catalysts, either led to over-reduction or to no reaction. Transfer hydrogenation using HC0₂H or H₂ over 1096 Pd/C led to over-reduction. On the other hand, use of HC0₂NH₄ with either 10% Pd/C²³ or RaNi returned the starting material. Remarkably, HC0₂H with catalytic RaNi gave diastereomeric amine 9 in 88% yield (Figure 7, structure by X-ray).

 

Conversion of amine 9 into racemic core 10 (D-ring) was accomplished by an intramolecular reductive amination

between Cl6 and the nitrogen via in situ hydrolysis of the acetal group using 0.5 N aqueous HC1 at 100 °C followed by formation of an iminium ion and its reduction with NaCNBH₃ into a racemic mixture of amines 10 (8,14dihydronorsalutar- idine and norisosinomenine). No hydrolysis of the methyl enol ether occurred under these conditions. A yield of 70% was obtained for 10 which upon treatment with 37% H₂CO(_aq), NaCNBH₃, and AcOH in EtOH²⁵ led to N-methylation to give 11 as a racemic mixture of isosinomenine and 8,14* dihydrosalutaridine in 91% yield (Figure 8, structure by X-ray).

The strategy presented here is an efficient (17% from 1, 10 steps) racemic synthesis of the aforementioned 8,14-dihydro- morphinandienone alkaloids. The synthesis furnishes the correct oxidation level of the target compounds by avoiding the biomimetic strategy of o,p-phenolic coupling. A unique route to a Henry—Michael—dehydration cascade has been developed where a variety of other conditions failed. The resultant aliphatic nitro group could be reduced selectively only under transfer hydrogenation conditions. The current strategy is complementary to that from our group for the synthesis of codeine⁹ in that it begins with the C6 oxygen already in place, obviating the need for its later introduction over several steps. A one-step conversion of 7 to 9, a one-pot conversion of 9 to 11, and an asymmetrical conversion of 5 to 6 are topics for future consideration. Conversion of 8,14-dihydrosalutaridine into salutaridine (i.e., oxidation of C8—C14 into a double bond as exemplified by conversion of ocobotrine into sinoacutine via cr-bromination-dehydrobromination ^a) would allow for its subsequent transformation into thebaine²⁶ and codeine,²⁷ providing a practical synthesis of these iconic structures.

Изменено 19 Октября, 2014 в 18:24 пользователем timur2312

[NLVN]

А вы сами то какой инглиш учите, что перевести не можете?

[timur2312]

немецкий

[NLVN]

Это кусок обзора по реакциям восстановления?

[timur2312]

да

[chebyrashka]

Вам это влетит в копеечку. Просто так никто переводит не будет.

[mypucm]

"Селективное уменьшение нитро-группы в 8 соединении было очередным вызовом для майора". 

 

Пардон, просто прикалываюсь...