Retrosynthetic analysis enamines

L-idose 293, 311 ff. imine formation 57 imine-enamine tautomerization 467 iminium-RhH jt complex 351 f. imipenem 348 indoline ligands 681, 684 indolizomycin 47 Iff. -.retrosynthetic analysis 472ff. 

A ketone 302 may be produced from the hydrolysis of an enamine 303 (equation 107). Applying the same retrosynthetic analysis as in the previous examples, an a,/3-unsaturated compound 304 is obtained as the starting material. 

The first stereocontrolled syntheses of juvabione are described in Schemes 13.11 and 13.12. Scheme 13.10 is a retrosynthetic analysis corresponding to these syntheses. These syntheses have certain similarities. Both start with cyclohexenone. There is a general similarity in the fragments that were utilized, but the order of construction differs. In the synthesis shown in Scheme 13.11, the crucial step for stereochemical control is step B. The first intermediate is constructed by a [2 + 2] cycloaddition between reagents of complementary polarity, the electron-rich enamine and the electron-poor enone. The cyclobutane ring is then opened in a process which corresponds to retrosynthetic step Ha => Ilia in... 

Fig. 14.2 shows a partial retrosynthetic analysis for the three routes A, B,and C discussd and reveals many unexplored possibilities for the synthesis of morphine. Continued attempts have teen made to find new routes to its ring sytem. Thus a photocyclisation of an aryloxyenone (Fig. 14.2, scheme type D) (ref. 187), a methodology based upon the use of a metallated enamine (ref. 188), and a route employing a vanillin derivative and its reaction with a 2-allylcyclohex-2-ol have been described, the last two of which gave racemic morphine (ref. 189). 

How would you synthesize each of the following, using the Robinson annulation Show both your retrosynthetic analysis and a forward reaction scheme, taking care to use enamines, activating and protecting groups as appropriate ... 

With the following retrosynthetic analysis, we can identify the starting reagents necessary to prepare this product via a Stork enamine synthesis ... 

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