Intramolecular esterification

Hydroxy acids compounds that contain both a hydroxyl and a carboxylic acid function have the capacity to form cyclic esters called lactones This intramolecular esterification takes place spontaneously when the ring that is formed is five or six membered Lac tones that contain a five membered cyclic ester are referred to as 7 lactones, their six membered analogs are known as 8 lactones... 

Section 19 15 An intramolecular esterification can occur when a molecule contains both a hydroxyl and a carboxyl group Cyclic esters are called lactones and are most stable when the nng is five or six membered... 

Ring closure resulting from attack of a heteroatom on a carboxyl group or its equivalent is merely a case of intramolecular esterification or amide formation. The y-butyrolactones or pyrrolidones obtained from such reactions are usually regarded as the province of aliphatic chemistry, so only a few examples are offered by way of illustration in Scheme 15. 

Inter and Intramolecular nucleophiKc displacement o< alcohols wHh inversion by means of cHethyi azo cartMxylate (DEAD)-triphenylphosphine and a nucleophile. Also dehydration, esterification of alcohols or alkylallon of phenols,... 

If the following molecule is treated with acid catalyst, an intramolecular esterification reaction occurs. What is the structure of the product (Intramolecular means within the same molecule.)... 

Fradet227,232, in an esterification study on models, examined the reaction of octadecanoic acid with tetrabutoxytitanium. He found that a small amount of butyl octadecanoate is formed (absorption of the ester carbonyl at 1740 an-1) and that the carboxy absorption at 1710 cm-1 disappears completely. Simultaneously, two bands appear at 1560 and 1450 an-1, which is in agreement with Yoshino302. The ratio of the intensity of each of these two peaks to the intensity of ester peak (1740 cm-1) does not change when the concentration of the solution used in the spectroscopic study is varied consequently, the interaction between carbonyl and titanium is most probably intramolecular ... 

Some chemical properties of boryloxyphenylenephosphines (192) have been studied [Eq. (141)]. In Balueva et al. (91IZV2397) the intramolecular trans-esterification of phenylboric acid, a phenyl ester with a-... 

Miiller and Vargha65 reported that treatment of 1,6-di-O-benzoyl-D-mannitol (29) with p-toluenesulfonyl chloride gave 2,5-anhydro-l,6-di-0-benzoyl-3,4-di-0-p-tolylsulfonyl-D-glucitol (67). The formation of this compound may be the result of a favored p-toluenesulfonyla-tion at the 2(5)-hydroxyl group, followed by intramolecular cycliza-tion and subsequent esterification by the excess of the reagent. This... 

Isoe, S., Katsumra, S., and Kimura, A., Total synthesis of ( )-jolkinolide A, B, and E utilizing a new mild esterification followed by intramolecular Wit-tig-Horner reaction, Tetrahedron, 45, 1337, 1989. 

Recently, dipolarophile 1)13 (fumaronitrile) (777) has been used in the synthesis of indolizine lactone (677). Both, intermolecular and intramolecular cycloadditions were studied. Intermolecular 1,3-cycloaddition of nitrone (671) to D13 led to the formation of isoxazolidine (672). Subsequent deprotection and esterification of the obtained alcohol (673) with (674) gave isoxazolidine (675) in 65% yield. Ester (675), when refluxed in xylene for 10 min, after elimination of fumaronitrile by cyclo-reversion, underwent spontaneously intramolecular cycloaddition to give the tricyclic cycloadduct (676) in 84% yield (Scheme 2.291). 

The understanding of the SSP process is based on the mechanism of polyester synthesis. Polycondensation in the molten (melt) state (MPPC) is a chemical equilibrium reaction governed by classical kinetic and thermodynamic parameters. Rapid removal of volatile side products as well as the influence of temperature, time and catalysts are of essential importance. In the later stages of polycondensation, the increase in the degree of polymerization (DP) is restricted by the diffusion of volatile reaction products. Additionally, competing reactions such as inter- and intramolecular esterification and transesterification put a limit to the DP (Figure 5.1). 

COOR Penicillins Esterification of the C(3) carboxy group Electron-withdrawing effect makes /3-lactam carbonyl C-atom more electrophilic, and intramolecular acylamido participation (see Fig. 5.9) Increased ca. 16-fold [91]... 

Besides direct solid phase fixation, the functional OH-group of 49 may be used for further transformations. Esterification with acetyl chloride at the OH-linker (Scheme 27) leads to 50, providing a heteroscorpionate ligand with the protected OH-linker. An intramolecular hydrogen bridge is found in the X-ray structure [d(01-N21) = 2.478 (3) A] between the carboxylic acid and the pyrazole nitrogen (Fig. 32b). 

The first three retrosynthetic cleavages are formation of the C7-C8 aldol by intramolecular chromium-Reformatsky reaction of linear precursor 51, esterification between northern and southern half building blocks and Wit-tig reaction of phosphonium salt 52 known from Mulzer s work [85] and northern half precursor 53. The final disconnections were placed at the C2-C3 aldol in 51 (again to be formed by chromium-Reformatsky reaction, here between bromoacetimide 56 and aldehyde 57) and the C14-C15 bond by alkylation of acetoacetate 54 with neryl bromide 55. 

Various aldehydes 184 and alcohols have been shown to be competent in the redox esterification of unsaturated aldehydes in the presence of the achiral mesityl triazo-lium pre-catalyst 186. Both aromatic and aliphatic enals participate in yields up to 99% (Table 13). Tri-substituted enals work well (entry 3), as do enals with additional olefins present in the substrate (entries 4 and 7). The nucleophile scope includes primary and secondary alcohols as well as phenols and allylic alcohols. Intramolecular esterification may also occur with the formation of a bicyclic lactone (entry 8). 

The preparation of lactones via intramolecular catalytic esterification can be carried out by the Tishchenko reaction of dialdehydes. Alkaline earth metal oxides have been shown to be active not only for the intermolecular Tishchenko reaction, but also for the intramolecular Tishchenko lactonization. Thus, these solid catalysts have been applied for the Tishchenko reaction of o-phthalaldehyde to phthalide 182) (Scheme 34). 

---