Assuming that you have available only alcohols or esters...

Assuming that you have available only alcohols or esters containing no more than four carbon atoms, show how you might synthesize each of the following compounds. Begin by writing a retrosynthetic analysis for each. You must use a Grignard reagent at one step in the synthesis. If needed, you may use oxirane and you may use bromobenzene, but you must show the synthesis of any other required organic compounds. Assume you have available any solvents and any inorganic compounds, including oxidizing and reducing agents, that you require. (a)(FIGURE CANNOT COPY) (b)(FIGURE CANNOT COPY) (c)(FIGURE CANNOT COPY) (d)(FIGURE CANNOT COPY) (e)(FIGURE CANNOT COPY) (f)(FIGURE CANNOT COPY) (g)(FIGURE CANNOT COPY) (h)(FIGURE CANNOT COPY)

Assuming that you have available only alcohols or esters containing no more than four carbon atoms, show how you might synthesize
each of the following compounds. Begin by writing a retrosynthetic analysis for each. You must use a Grignard reagent at one step in the synthesis. If needed, you may use oxirane and you may use bromobenzene, but you must show the synthesis of any other required organic compounds. Assume you have available any solvents and any inorganic compounds, including oxidizing and reducing agents, that you require.
(a)(FIGURE CANNOT COPY)
(b)(FIGURE CANNOT COPY)
(c)(FIGURE CANNOT COPY)
(d)(FIGURE CANNOT COPY)
(e)(FIGURE CANNOT COPY)
(f)(FIGURE CANNOT COPY)
(g)(FIGURE CANNOT COPY)
(h)(FIGURE CANNOT COPY)

Key Concepts

Functional Group Interconversion

This concept involves transforming one functional group into another in a controlled and predictable manner. In synthesis planning, converting readily available alcohols or esters into more reactive intermediates like carbonyl compounds expands the available reaction types. This step is crucial when the initial materials are limited in carbon number or type and must be modified to serve as effective building blocks.

Carbonyl Addition Reactions

Closely related to the Grignard reaction, carbonyl addition reactions involve nucleophilic attack on a carbonyl group to form alcohols. These reactions are fundamental in creating new carbon–carbon bonds and are particularly useful when synthesizing alcohol derivatives from carbonyl precursors, a common theme in designing synthesis routes with limited starting materials.

Epoxide Ring Opening

The opening of oxiranes (epoxides) is a valuable transformation that provides a route to form more extensive carbon chains and introduce functionality. Epoxides are highly strained and reactive toward nucleophilic attack, and their ring opening reactions can lead to the formation of alcohols or other subunits. This reaction is particularly useful when synthesizing target molecules that require extending carbon skeletons under mild conditions.

Retrosynthetic Analysis

This concept involves breaking down a complex target molecule into simpler precursor structures. The reverse thinking strategy identifies strategic bonds whose disconnection leads back to readily available or simpler starting materials, allowing the synthesis to be planned in logical steps. It is essential for mapping out the synthesis pathway, especially when the synthetic approach is constrained by starting material limitations.

Grignard Reaction

The Grignard reaction is a key method for forming carbon–carbon bonds by attacking electrophilic carbon atoms on compounds such as carbonyls. Using Grignard reagents allows the construction of more complex molecules from simpler ones, and in this context, it is specified as a necessary step in the synthesis. The reaction’s versatility and reliability make it a cornerstone in organic synthesis.

Transcript

00:01 So here we're taking a look at retro -synthetic reactions.

00:04 We're essentially given a target molecule and we're just having to work backwards.

00:08 So we take a look at our first structure, make our synthetic cut, draw our retro synthesis arrow, and now we draw our components, where we have two methyl, propan -one -ol and bromobenzene.

01:06 So sort of reagents that we're going to be needing here is we're going to be needing mg and et -2o for this conversion to get to, phenyl magnesium bromide.

01:18 You need pcc and ch2 cl2 to get from our alcohol to our aldehyde.

01:26 Then we react these two together in the presence of et2o and h3o plus of proton source.

01:35 Then in the second step we have pcc and ch2 cl2.

01:40 So in the next example we have we can make two synthetic cuts.

02:37 It's moving straight on to our next example just to say very of time here we've already discussed the sorts of reagents that we need for these types of chemical reactions so all we're going to be focusing on is the structures themselves to make our synthetic cut green yard reagent and this is generated using a alcohol starting material and our other starting material also contains an alcohol so we're just chemically transforming our starting target molecule that we have into a primary alcohol because we can achieve this chemical transformation here in reverse.

04:08 Then we can make our chemical cut.

04:13 Now we can think about drawing our starting materials.

04:37 One of our starting materials is an epoxide.

04:47 We just insert a new page.

04:52 Moving on to our next example here.

05:13 And first have a chemical transformation into an alcohol, then we make a new page.

05:22 Make our synthetic cut.

05:25 Now we'll draw our materials and an epoxide.

05:37 Well we've seen this step before we go from magnesium bromide to just a bromide containing molecule and then we use the alcohol form...