Amines from tertiary alcohols, table

The action of the tin catalyst was found to be quite different from the action of the tertiary amine catalyst. In the presence of the amine catalyst the reactivity of the phenol and benzyl alcohol was approximately equal (see Table IV). In the case of DBTDL, the reactivity ratio was similar to that of the non-catalyzed reaction, which indicates that the polarization of the isocyanate by the tin catalyst due to complex formation presumably played an important role in the reaction catalysis (see Table VI). 

A highly versatile auxiliary is the Evans oxazolidinone imide (Figure 5.4c, see also Scheme 3.16), available by condensation of amino alcohols [86,87] with diethyl carbonate [86]. Deprotonation by either LDA or dibutylboron triflate and a tertiary amine affords only the Z(0)-enolate. Scheme 5.12 illustrates open and closed transition structures that have been postulated for these Zf0)-enoIates under various conditions, and Table 5.4 lists typical selectivities for the various protocols. The first to be reported (and by far the most selective) was the dibutylboron enolate (Table 5.4, entry 1), which cannot activate the aldehyde and simultaneously chelate the oxazolidinone oxygen [75]. Dipolar alignment of the auxiliary and approach of the aldehyde from the Re face of the enolate affords syn adduct with outstanding diastereoselection, presumably via the closed transition structure illustrated in Scheme 5.12a [75]. The other syn isomer can be formed under two different types of conditions. In one, a titanium enolate is postulated to chelate the oxazolidinone... 

Path d) retention of corfguration. Alcohols are formed in low yield in the nitrous acid deamination of amines in acetic acid, and they have been isolated in only a few instances. The alcohol represents the intramolecular product of the deamination and with the exception of the norbomanols, which will be discussed later, they are formed from secondary and tertiary carbinamines with overall retention of configuration (Table 12). The results are so striking and so similar to those of the nitrosoamide decomposition (Tables 6 and 7) that we feel a common reaction mechanism must be involved. Paths (d) and (g) (equation 146) involving predominant collapse on the front side of the cation are proposed for the formation of the alcohoP° -i3i-i °. 

Closely related to the mixed oxides are the organogermanium alkoxides, which contain the linkage Ge-O-C and may be considered as alkoxide counterparts of the organogermanium halides. Indeed, they may readily be made from such halides by the action of sodium or lithium alkoxides, or by the action of the alcohols themselves if an HCl acceptor such as a tertiary amine also is used. Conversion reactions of organogermanium alkoxides with higher alcohols also are possible. The physical properties of some such alkoxides are given in Table 18. 

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