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Date: 26-1-2020
1313
Date: 21-7-2016
2826
Date: 20-1-2020
1192
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Alkenes are oxidized to cis-1,2-diols by osmium tetroxide (OsO4). The stereospecificity is due to the formation of a cyclic osmate ester intermediate. Osmium tetroxide can be used directly, but it is normally used in catalytic amounts, and is regenerated by N-methylmorpholine-N-oxide.
Examples
Questions:
1. Give the major product.
2. What is the product in the dihydroxylation of (Z)-3-hexene?
3. What is the product in the dihydroxylation of (E)-3-hexene?
4. Draw the intermediate of this reaction.
5. Fill in the missing reactants, reagents, and product.
1. A syn-1,2-ethanediol is formed. There is no stereocenter in this particular reaction. The OH groups are on the same side.
2. Meso-3,4-hexanediol is formed. There are 2 stereocenters in this reaction.
3. A racemic mixture of 3,4-hexanediol is formed. There are 2 stereocenters in both products.
4. A cyclic osmic ester is formed.
5. The Diels-Alder cycloaddition reaction is needed in the first box to form the cyclohexene. The second box needs a reagent to reduce the intermediate cyclic ester. The third box has the product: 1,2-cyclohexanediol.
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إدارة الغذاء والدواء الأميركية تقرّ عقارا جديدا للألزهايمر
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شراء وقود الطائرات المستدام.. "الدفع" من جيب المسافر
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بالصور: الامين العام للعتبة الحسينية المقدسة يجري جولة ميدانية للوقوف على آخر الاستعدادات الخاصة بمراسيم تبديل راية الإمام الحسين (ع)
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