Carbon-nitrogen-oxygen bicycle

The versatility of the Diels-Alder reaction becomes especially obvious, when considering the hetero-variants. One or more of the carbon centers involved can be replaced by hetero atoms like nitrogen, oxygen and sulfur. An illustrating example is the formation of the bicyclic compound 31, by an intramolecular hetero-Diels-Alder reaction ... 

One atom incorporation reactions are discussed in Chapter II subdivided into carbon, nitrogen, and oxygen incorporation. A few of these reactions are discussed in other sections. Because of their special reactivity most of the three-membered ring compounds used for expansion are combined in Chapter III. Reactions with four-membered intermediates are collected in Chapter IV Reactions of the type 1/9 — 1/10 will be found in Chapter V and those of 1/7 —> 1/8 (see Scheme 1/1) in Chapter VII. Bicyclic starting materials will be discussed in... 

Rings containing boron, carbon, nitrogen and oxygen.- Bicyclic boroxazolidones, e.g. 

Chapter 21 introduces aromatic hydrocarbons and their unique chemistry. In another class of aromatic compounds, heteroatoms replace one or more of the ring carbons. These compounds are collectively known as heterocycles or heterocyclic aromatic compounds, and they comprise a class of compounds so large that an entire course is easily built around their chemistry. Heterocycles are seen in several places in this book, including a brief introduction to their nomenclature in Chapter 5 (Section 5.6) and in Chapter 8 (Section 8.9). The most common heterocycles include five- and six-membered monocyclic derivatives that contain nitrogen, oxygen, or sulfur. Several important bicyclic derivatives contain nitrogen. The use of heterocycles in medicine and industry is extensive. This chapter will expand the aromatic chemistry from Chapter 21 and introduce the world of heterocyclic chemistry. 

Isoelectronic replacement of a carbanionic carbon by a heteroatom gives much more stable compounds, and such 5,5-bicyclic aromatic systems have received considerable attention. In these compounds, sulfur, nitrogen and oxygen can also be incorporated into fully conjugated systems, unlike the 5,6-compounds, where only nitrogen can be used. Because of the variety of such systems, it is difficult to generalise about reactivity, but electrophilic substitution, which can take place in either ring, has been most widely reported with occasional examples of nucleophilic displacements and lithiations. Some representative reactions and self-explanatory syntheses are shown below." ... 

The reaction has been carried out with differently substituted alkynol derivatives and oxygen-, nitrogen-, and carbon-centered nucleophiles and applied to the synthesis of enantiomerically pure [3.3.1]bicyclic systems from the chiral pool. The mechanism parallels the one proposed for the hydroalkoxylation/hydroarylation sequence. 

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