Current Organic Synthesis - Volume 3, Issue 2, 2006

Radical ring closure reactions by intramolecular addition of a radical to a tethered double bond afford a new cyclized radical intermediate that can be reduced, or further react with different reagents to yield substituted-cyclic compounds. The applications of SRN1 reactions are broad in scope, encompassing the utilization of poorly reactive substrates. We undertake a compilation to cover recent literature of these reactions and their synthetic applications.

Natural carbohydrates have complex structures including many kinds of monosaccharide units, which are very difficult and costly to generate by chemical synthetic approaches. Over the years, enzymatic approaches have been gaining popularity for the synthesis of oligosaccharides and glycoconjugates, and it is becoming increasingly feasible to produce complex carbohydrates in large scale, following enzymatic biosynthetic pathways.

Methods of preparing 1,1'-bi-2-naphthol (BINOL) in optically active form, are reviewed. Preparation of this compound and its derivatives through both resolution and asymmetric synthesis, are discussed. Methods of determining the enantiomeric excess of samples of optically active BINOL, both through chromatographic and spectroscopic means, are also reviewed.

Phosphazenyl-stabilized carbanions are polyfunctional synthons, which combine in the same molecule a nucleophilic center adjacent to the phosphorus atom with a variety of functional groups linked to the nitrogen atom. The substituents on the nitrogen have the capability of tuning the reactivity of the anion and may also intervene at a given point of the synthetic pathway. This is a distinguishing feature of Cα-lithium phosphazenes with respect to all other phosphorus-stabilized carbanions: they have found application in organic (as for example, in the synthesis of olefins, functionalized open-chain compounds, heterocycles containing phosphorus atoms either in the ring or as appendages of the cyclic system) and inorganic chemistry (e.g. preparation of novel catalysts and polymers with improved properties with respect to the parent polymer).

This articale is the first attempt to review chemical transformation of one most interesting synthon among strained, saturated hydrocarbons - tetracyclo[3.2.0.02,704,6]heptane (quadricyclane, Q), from the point of view of synthetic organic chemistry. Thermal [2+2+2] cycloaddition reactions of Q with olefins, acetylenes, carbonyl, nitrogen, sulfur containing compounds, carbenes and silenes along with cycloaddition reactions involving transition metals are reviewed in a first part. Second part of the review covers photochemical transformations, ionic reactions (electrophilic and nucleophilic), oxidation and reduction of Q.