Leading direction

Note that the exact adiabatic functions are used on the right-hand side, which in practical calculations must be evaluated by the full derivative on the left of Eq. (24) rather than the Hellmann-Feynman forces. This forai has the advantage that the R dependence of the coefficients, c, does not have to be considered. Using the relationship Eq. (78) for the off-diagonal matrix elements of the right-hand side then leads directly to... 

METHOD 9 -This is a little, oddball method that will transforms piperonal or benzaldehyde into a quasi-cydic intermediate that will lead directly to MD-P2P or P2P [25],... 

The most suitable synthetic method for these products is the heterocyc-lization reaction of N-thioacyl derivatives of amino acids (202) with phosphorus tribromide (378, 442-450, 559, 560) or anhydrous trifluoroacetic acid (448, 449, 451, 452) (Scheme 103). Treatment of N-thioacyl amino acids with acetic anhydride leads directly to the thiazolylacetate without isolation of an intermediate thiazolinone (365. 452). 2-Alkoxy-derivatives of A-2-thiazoline-5-one, however, can be obtained without acetylation by this method (453, 454). 

Substitution of an ester of dithiocarbamic acid such as alkyl or benzyl ester (171), or their salts leads directly to 2-substituted mercaptothiazoles (172) (Scheme 87) (272, 461). Some of these compounds have an antifungal activity (561). 

Scheme 98) (523). Hydrogen chloride is unsatisfactory as a cyclizing agent, whereas hydrogen iodide causes further reduction and leads directly to derivatives of the previously inaccessible 4-aminothiazoles (see Section VII. 2). 

In one method treatment of a solution containing the N protected and the C protected ammo acids with N N dicyclohexylcarbodiimide (DCCI) leads directly to peptide bond formation... 

Analysis of biological activity does not automatically lead directly to a corrosion-rate measurement. However, with detection and correlation with process conditions, such information may also lead to improvements in the corrosion lifetime of the process equipment. 

Taking these methylene groups into account, interpretation of the HH COSY plot leads directly to the HH relationships C even if the protons at Sh = 2.34 and 4.58 do not show the expected cross signals because their intensity is spread over the many multiplet lines of these signals. 

Two ff-intermediates are conceivable. A would lead directly to product on deprotona-... 

This compound is less stable than 5 and reverts to benzene with a half-life of about 2 days at 25°C, with AH = 23 kcal/mol. The observed kinetic stability of Dewar benzene is surprisingly high when one considers that its conversion to benzene is exothermic by 71 kcal/mol. The stability of Dewar benzene is intimately related to the orbital symmetry requirements for concerted electrocyclic transformations. The concerted thermal pathway should be conrotatory, since the reaction is the ring opening of a cyclobutene and therefore leads not to benzene, but to a highly strained Z,Z, -cyclohexatriene. A disrotatory process, which would lead directly to benzene, is forbidden. ... 

The interaction of one solute molecule with two solvent molecules would lead directly to a second order equation in terms of concentration but more experimental evidence is required before this can be confirmed. 

Since alkaline decomposition of p-toluenesulfonylhydrazones of steroid 12-ketones leads directly to 14(13 I2) jr e >-13(17)-enes whereas solvolysis of 12j5-mesylates gives mixtures of 13(18)- and 13(17)-enes, the former approach is preferred for the preparation of C-nor-D-homosteroids. If the particular system under consideration is not stable to base at elevated temperatures, the milder solvolysis method could be used. Either approach starts with a 12-oxygenated steroid. Additional base-stable functional groups should be compatible under the conditions for the rearrangement process. 

Overpressure can lead directly to all three hazards. It can lead directly and immediately to injury, to fire or explosion if there is an ignition source, and to pollution if there is not enough containment. Therefore, we must have a very high level of assurance that overpressure is going to have a very low frequency of occurrence. 

Fire tubes can lead to fire or explosion if there is a leak of crude oil into the tubes or failure of the burner controls. An explosion could be sudden and lead directly to injury. Therefore, a high level of safety is required. 

Leaks cannot lead directly to personal injury. They can lead to fire or explosion if there is an ignition source and to oil pollution if there is inadequate containment. Both the immediacy of the hazard developing and the magnitude of the hazard will be smaller with leaks than with overpressure. Thus, although it is necessary to protect against leaks, thi.s protection will not require the same level of safety that is required to protect against overpressure. 

Discussing pore size selection of columns leads directly to the issue of using single porosity columns or so-called linear or mixed-bed columns, which contain mixtures of different pore sizes in a single column (3,19). Both types of columns have advantages and disadvantages, as shown in Table 9.6. 

The FMO approach shown in Figure 15.19 again indicates that the 4s - - 2s interaction should lead directly to formation of two new bonding a-bonds, i.e. this is an allowed reaction. The preference for a concerted 4s + 2s reaction is experimentally supported by observations which show that the stereochemistry of the diene and dieneophile is carried over to the product, e.g. a trans,frans-l,4-disubstituted diene... 

The same conclusion may again be reached by considering only the HOMO orbital. Figure 15.24. For the conrotatory path the orbital interaction leads directly to a bonding orbital, while the orbital phases for the disrotatory motion lead to an anti-bonding orbital. 

A useful and possibly more general alternative to the Lwowski synthesis- of 1,3-diphenylisoindoles involves condensation of a l,2-dibenzoyl-l,4-cyclohexadiene (e.g., 55) with ammonia or a primary amine. Cyclohexadiene derivatives of this type are easily prepared by Riels-Alder addition of a 1,3-diene to dibenzoylacetylene, and these adducts lead directly, and in high yield, to the corresponding isoindoles (56). The reaction is closely related to the well-known synthesis of pyrroles by condensation of 1,4-diketones with ammonia. 4,7-Dihydro- and 4,5,6,7-tetrahydroisoindoles (57 and 58) have been... 

Further investigation of pyrrole polymer would be of considerable interest. Rather similar to the foregoing hypothetical reaction is the attempted quaternization of (21), which leads directly to (22), no quaternary salt surviving at all. ... 

Oppenauer oxidation of the enol ether (34) affords the corresponding 17 ketone (37) (the enol ether is stable to the basic oxidation conditions). This ketone affords the corresponding 17a-ethynyl compound on reaction with metal acetylides. Hydrolysis of the enol ether under mild conditions leads directly... 

A thiazole derivative that incorporates a fragment of the amphetamine molecule shows some CNS stimulant activity more specifically, the compound antagonizes the depression caused by overdoses of barbiturates and narcotics. Reaction of benzalde-hyde with sodium cyanide and benzenesulfonyl chloride gives the toluenesulfony1 ester of the cyanohydrin (141). Reaction of this with thiourea leads directly to aminophenazole (143) It is probable the reaction proceeds by displacement of the tosylate by the thiourea sulfur to give 142 addition of the amino group to the nitrile followed by tautomerization affords the observed product. ... 

---