Birch reduction chemoselectivity

How would you convert this bromoaldehyde chemoselectively 4. Predict the products of Birch reduction of these aromatic into the two products shown compounds. 

The commonest form of chemoselectivity involves the preferential attack of electrophiles on electron-rich alkenes as in the ozonation of a Birch reduction product 19 used in chapter 15 to make a Z-alkene Z-20 R=Me and hence Cecropia juvenile hormone 5. 

Epoxide (36) can be made from (37) by chemoselective epoxidation of the more substituted and therefore more nucleophilic double bond. Non-conjugated diene (37) is an obvious Birch reduction product as both elearon-donating substituents are on the double bond and therefore away from the anions. 

The proposed synthetic route to TM 2.8 starts with anisole, which on methy-lation and Birch reduction affords a derivative of non-conjugated cyclohexadiene TM 2.8g. The importance and mechanism of this reaction are discussed in Sect.5.4. Chemoselective hydrogenation of one C=C bond is possible since the double bond in enol ether C=C-OMe is less reactive. TM 2.8f affords ester-aldehyde TM 2. 8e on ozonolysis (Scheme 2.20). 

Abstract Compounds with a 1,2-, 1,4- and 1,6-dioxygen pattern and related bifunctional structures are presented. Disconnection of the internal bonds results in illogical synthons because of the mismatch of charges in the patterns with an even number of C atoms between the functional groups. Three-membered heterocyclic rings are presented as an important class of illogical nucleophiles in the retrosyn-thesis of the 1,2-difunctional pattern. Retrosynthesis of the 1,6-dicarbonyl pattern by reconnection and rctro-Birch reduction of the aromatic building block is related to chemoselective Birch reduction and ozonolysis in the synthetic route. The retrosynthesis and synthesis of salbutamol and asymmetric synthesis of —)-frontalin are presented. 

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