Strategy key reaction

The Reconnective Strategy The Key Reaction Strategy Intramolecular Diels-Alder Routes Intermolecular Diels-Alder Routes Routes Based on 1,3-Dipolar Additions Syntheses Based on Claisen and Cope Rearrangements Syntheses Based on Other Key Reactions... 

This strategy resulted in a direct and stereoselective synthesis of the dolestane skeleton, in which the relative configuration at the quaternary C-5 and C-12 carbons was established. It was shown that the key reaction produced the tricyclic compound slereospecifically in a remarkably high chemical yield57. 

Within the diastereomeric switch sequences, the corresponding trans-diols become accessible either using a Mitsunobu inversion or a reversible Diels-Alder cyclization as key reaction step [249,250]. This synthetic strategy is complementary to an approach involving metabolic engineering of E. coli via the chorismate/ isochorismate pathway [251]. 

Consider an FGA strategy for (30) in which you add a carbonyl group somewhere in the molecule so that it can be made by a key reaction from simple starting materials. 

Addition of, say, a C02Et group would allow Diels-Alder disconnection leading eventually to cycloheptanone. A better strategy is to add a carbonyl group to make an enone (31) with Robinson annelatlon as the key reaction. Analysis... 

Retrosynthetic analysis of 5 and 6 yielded ketone 7 as pivotal intermediate. A key reaction for the synthesis of 7 was the auxiliary-controlled, di-astereoselective biaryl coupling of a phenyl magnesium bromide (from 8 or 9) with aryloxazoline 10 (Scheme 1). This coupling strategy was developed in the Meyers laboratory [12] and previously applied to the enantioselective synthesis of other naturally occurring biaryl lignans, such as steganone [13]. 

Tetrahydroisoquinolonic acids were generated in good to excellent yields by the multicomponent reaction of benzaldehydes, amines, and the cyclic anhydride 65 (Equation 197) <2003T1805>. The key element in this example is the use of ionic liquids and in other examples of the same reaction strategy, the high diastereoselectivity achieved <2005JOC350>. 

After the preparation of the 2-methylcysteine compounds, the ring closure to the thiazoline 33 is the next step in most of the synthetic strategies. The key reactions used are summarized in Scheme 9. 

The synthetic strategy of cembrane-type diterpenes include (1) efficient methods for the construction of a 14-membered carbocyclic ring, (2) functional group assembly, and (3) stereochemistry control as the key reactions. Because the... 

A second method that has been invaluable for accessing glycans is chemical synthesis (see cross references Glycan synthesis, key reaction of Glycan synthesis, key strategies for Glycan synthesis, protection and deprotection steps of and... 

Glycan Synthesis, Key Reactions of Glycan Synthesis, Key Strategies for Glycan Synthesis, Protection and Deprotection Steps of... 

Epoxides are key chiral synthetic intermediates and their enantioselective preparation by oxidation of achiral alkenes is a key reaction in many synthetic strategies. Sharpless asymmetric epoxidation is suitable for most allylic alcohols [26, 27], but few general procedures exist for unfunctionalized olefins. Jacobsen s manganese salen-mediated epoxidation is suitable for and gives good selectivities with Z-olefins (85 to 90% ee) [28]. The enzyme chloroperoxidase... 

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