The disconnections we have made so far have all been of C–O, C–N, or C–S bonds, but, of course, the most important reactions in organic synthesis are those that build the carbon skeleton by forming C–C bonds. We can analyse C–C disconnections in much the same way as we’ve analysed C–X disconnections. Consider, for example, how you might make the simple compound in the margin, which is an intermediate in the synthesis of a carnation perfume. The only functional group is the triple bond, and we shall want to use the chemistry of alkynes to show us where to disconnect. You know that alkylation of alkynes is a reliable reaction, so a sensible disconnection is next to the triple bond.

It’s often a good idea to start retrosynthetic analysis of target molecules containing iso lated double bonds by considering FGI to the alkyne because C–C disconnections can then become quite easy. The cis-alkene below is an intermediate in the synthesis of a com ponent of violet oil. FGI to the alkyne reveals two further disconnections that make use of alkyne alkylations. The reagent we need for the fi rst of these is, of course, the epoxide as there is a 1,2-relationship between the OH group and the alkyne.

The next example is the pheromone of the pea-moth, and can be used to trap the insects. After disconnecting the ester, FGI on the trans double bond gives an alkyne.

Disconnection on either side of the alkyne leads us back to a bromo-alcohol alkylating agent. In the synthesis of the pheromone, it turned out to be best if the hydroxyl group was protected as its THP ether. You should be able to think of other alkylation-type reactions that you have met that proceed reliably and therefore provide a good basis for a disconnection— the alkylation of enolates of esters or ketones.

اخر الاخبار

اخبار العتبة العباسية المقدسة

مستشفى الكفيل يعلن انضمامه لمشروع الضمان الصحي الحكومي

المجمَع العلمي يقيم مسابقة الكوثر الخاصة بترتيل القرآن الكريم في كربلاء

قسم الشؤون الفكرية والثقافية يُصدر العدد الثالث والعشرين من مجلّة (أوراق معرفية)

قسم التربية والتعليم يُطلق الموسم التدريبيّ الصيفيّ لملاكات مجموعة العميد التربوية

المزيد

الآخبار الصحية

اختراق علمي.. دواء يؤخر ظهور السكري من النوع الأول لسنوات

هذا ما يحدث لجسمك إن أهملت نظافة فراشك

لماذا تعتبر النساء أكثر عرضة للإصابة بألزهايمر من الرجال؟

لماذا يحذر الخبراء من الإفراط في تناول الفراولة؟

المزيد

الآخبار التكنلوجية

السيارات الكهربائية أنظف بنسبة 73% من سيارات الوقود

سيارة لوسِد الكهربائية تدخل "غينيس" بأطول مدى في العالم

نظرية جديدة تنسف كل ما نعرفه عن تشكل أول قارة في الأرض

منذ 37 ألف عام.. دراسة تكشف "أقدم أمراض" أصابت البشر

المزيد

مواضيع ذات صلة

Aromaticity survives when parts of benzene’s ring are replaced by nitrogen atoms

The Claisen ester disconnection: a 1,3-diO relationship needing two carbonyl groups

Aldol-style disconnections with N and O in a 1,3-relationship: I

Look out for concealed functional group relationships

Donor and acceptor synthons

Double disconnections can be a short cut

1,1C–C disconnections

1,2-Disconnections

Two-group disconnections are better than one-group disconnections

Amine synthesis using functional group interconversions

Functional group interconversion

Multiple step syntheses: avoid chemoselectivity problems