Addition reactions stereoselectivity

Within the last decade remarkable progress has been made with highly stereoselective addition reactions to C = C and C = 0 double bonds using chiral reagents. These reagents include ... 

Analogous stereoselective addition reactions of triorganogermanes to double bonds have teen described 63,64) they proceed with retention of configuration. 

The cyclopropylphosphonate anion undergoes the stereoselective addition reaction with aldehydes [106]. Although the Wittig-Horner elimination is not observed at this stage, the olefinic compounds are produced by treatment of the adduct alcohols 201 with NaH in the presence of 18-crown-6 as illustrated in Scheme 76. 

R. Batchelor, J. E. Harvey, P. T. Northcote, P. Teesdale-Spittle, and J. O. Hoberg, Heptanosides from galactose-derived oxepenes via stereoselective addition reactions, J. Org. Chem., 74 (2009) 7627-7632. 

In this Section we will mainly concentrate on stereoselective addition reactions involving the transformation of sp2 carbon atoms in C = C, C=O and C=N functions to sp3 hybridization these reactions do not include hydrogenation- and reduction-type transformations which were addressed in Sect. 2.1, 2.2, and 3.1. 

The fact that molecules in L-B films keep fairly rigid relative orientations (at least within a microdomain) is potentially useful for regio- and stereoselective addition reactions (Figure 8.23). Here a derivative of cirfnamic acid forms the head-to-head dimer in the photochemical cycloaddition reaction. 

Hashimoto, Y. Takaoki, K. Sudo, A. Ogasa-wara, T. Saigo, K. Stereoselective addition reaction of organolithium reagents to chiral imines derived from erythro-2-amino-l,2-diphenylethanol. Chem. Lett. 1995, 235-236. 

A clear evidence for a long-lived intermediate came from investigations of the stereoselectivity of the Paterno-Buchi reaction with cis and trans 2-butene as substrates, when acetone [52] or benzaldehyde [53] was used as carbonyl addends, complete stereo-randomization was observed. Acetelde-hyde and 2-naphthaldehyde showed stereoselective addition reactions which accounts for the singlet mi as the reactive state [43]. Fleming and Gao... 

Chapter 7 Regio- and Stereoselective Addition Reactions of Organolithiums... 

In the next two sections we examine a number of stereoselective addition reactions of boron and silicon allylic reagents to carbonyl compounds. 

OXAZOLIDINECARBOXYLATE has previously been described in Volume 70 of Organic Sytheses. An alternative procedure for the preparation of this compound is presented in this volume along with its use in a dia-stereoselective addition reaction with 2-TRIMETHYLSILYLTH1AZOLE to provide a compound bearing a 2-amino-1,3-diol substructure that appears in a variety of natural products. The conversion of abundantly available isosorbide into OSO ISOPROPYLIDENE-l ti-DIANHYDRO-d-GLUCITOL provides a potentially useful carbohydrate-deri ved material for the use in complex tetrahydrofuran synthesis. Finally, asymmetric reduction of an a,j9-unsaturated acylstannane with (R)-BINAL provides access to (S,E)-l-(METHOXYMETHOXY)-l-TRIBUTYLSTANNYL-2-BUTENE, an a-alkoxy allylstannane that has been used in enantioselective vicinal diol synthesis amongst other transformations. 

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