Secondary organometallic reagent

Amines are nucleophilic and easily oxidized. Primary and secondary amino groups are also sufficiently acidic that they are deprotonated by many organometallic reagents. If these types of reactivity are problematic, the amino group must be protected. The... 

The ring strain inherent in species XV increases its propensity for polymerization. A substantial number of organo-halogenocyclophosphazenes have now been polymerized (7-17). After polymerization, the halogen atoms can be replaced by treatment with alkoxides, aryloxides, primary or secondary amines, or organometallic reagents. 

Distinction between PL and ET mechanisms is not straightforward. Various experimental methods have been used so far to demonstrate the ET process, including spectroscopic detection of radical intermediates detection of products indicative of radical intermediates " and measurement of secondary deuterium " and carbonyl carbon kinetic isotope effects (KlEs) "" . The combination of several experimental methods, including KIE, substituent effect and probe experiments, was shown to be useful in distinguishing the ET process from the PL process for the addition reactions of the Grignard and other organometallic reagents . 

Organometallic reagents are better known for their involvement in the alkylations at ring nitrogen atoms in many heterocycles. However, under proper circumstances, they can promote addition to carbonyl groups. Such is the case when 68 is allowed to react with an excess of Me2BuMgLi at 0°C. The secondary alcohol 69 is obtained in fair yield (Equation 28) <20040L1991>. 

Addition of organometallic reagent to aldehyde preparation of secondary alcohols... 

F.2.1. Asymmetric Cross-Coupling of Secondary Alkyl Organometallic Reagents... 

Two principal approaches to the synthesis of an optically pure chiral secondary or tertiary alcohol from the reaction of an organometallic reagent with an aldehyde or ketone respectively are of current interest. In the first approach an alkyllithium or dialkylmagnesium is initially complexed with a chiral reagent which then reacts with the carbonyl compound. In this way two diastereo-isomeric transition states are generated, the more stable of which leads to an enantiometic excess of the optically active alcohol. This approach is similar in principle to the asymmetric reductions discussed in Section 5.4.1 (see also p. 15). Two chiral catalysts may be noted as successful examples, (10) derived... 

Phosphinous halides can be prepared from secondary phosphine oxides and phosphorus trichloride. The starting secondary phosphine oxides are easy to handle and can be prepared by treating readily available diethyl or dibutylphos-phite with an organometallic reagent.33... 

Monoalkylation of primary amines. A two-step sequence for this reaction involves conversion of the amine to the N-(cyanomethyl)amine (2) by reaction with chloroaceto-nitrile or with formaldehyde and KCN. Reaction of 2 with an organolithium or a Grignard reagent generates an unstable formaldehyde imint (a) that reacts with a second equivalent of the organometallic reagent to form a secondary amine (3). 

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