Convertible bonds definitions

The first mie is one which maximises the value of the convertible bond at each instant in time . In practice, the definition starts from the Modigliani and Miller theorem asserting that the firm value is independent of the conversion strategy. Therefore, given the conversion value equal to the conversion ratio times the share price at conversion, the value of the outstanding equity after conversion is given by the pre-conversion firm value divided by the number of shares outstanding shares when the bond is converted. 

It was anticipated all along that the vinylsilane residue could serve as a vinyl iodide surrogate. After protection of the C-14 secondary hydroxyl in 180 in the form of a triisopropylsilyl ether, the vinyltrimethylsilyl function can indeed be converted to the requisite vinyl iodide with AModosuccinimide (NIS) (see 180—>181, Scheme 43). Vinyl iodide 181 is produced stereospecifically with retention of the A17,18 double bond geometry. This transformation is stereospecific since the stereochemistry of the starting vinylsilane and the vinyl iodide product bear a definite relationship to each other.67b 75... 

As stated earlier, this technique relies essentially on the formation of covalently bonded diastereomers derived from a pair of chiral analytes (SAs pair of enantiomers) which have been converted to a pair of diastereomers using an optically pure chiral derivatizing agent (CDA) which, in this case, serves as a chiral selector (SO). In this context the definition of " optical purity of the CDA is critical (see Section 3.2.1.2.) and has to be evaluated by complementary methods. 

Figure 14.51 shows four Ireland-Claisen rearrangements that exhibit simple diastereose-lectivity (see Section 11.1.3 for a definition of the term). The substrates are two cis, trans-iso-meric propionic acid esters. The propionic acid esters in Figure 14.51 are derived from achiral allyl alcohols. This is different from the situation in Figure 14.50. However, these esters contain a stereogenic C=C double bond. Both the esters in Figure 14.51 can be converted into their 7 "-enolates with LDA inpureTHF (cf. Figure 13.16). Silylation affords the two T -con-figured O-allyl-O-silyl ketene acetals A and D, respectively. Alternatively, the two esters of Figure 14.51 can be converted into their Z -enolates with LDA in a mixture of THF and DMPU (cf. Figure 13.17). Treatment with rert-BuMe,SiCl then leads to the Z-isomers B and C of the O-allyl-O-silyl ketene acetals A and D, respectively.

From the synthetic point of view, oxidative photocyclization of these two types of enamides has a definite advantage in the construction of a polycyclic ring system with a double bond at the ring juncture in one step from the starting compounds. The photocyclized product can be readily converted to the cis-fused ring system by a facile catalytic reduction or to the fully aromatized lactam on dehydrogenolysis (19,20) as in the case of vV-benzoy-lenamines. 

Other divalent germanium compounds include salts of GeClj, such as the substituted pyrazolyl complexes [Ge2(pz )3][GeCl3] (8-XXII) which is obtained in the reaction of Ba(pz )2 with GeCl2-dioxane.148 There are also a sulfide, GeS, several thiolato complexes,149 and a white to yellow hydroxide of no definite stoichiometry that is converted by NaOH to a brown material that has Ge—H bonds. 

Cyclobutanes may be converted to alkenes thermally, the reverse of the [2 + 2] cycloaddition reaction. These retroaddition or cycloreversion reactions have important synthetic applications and offer further insights into the chemical behavior of the 1,4-diradical intermediates involved they may proceed to product alkenes or collapse to starting material with loss of stereochemistry. Both observations are readily accommodated by the diradical mechanism. Generation of 1,4-tetramethylene diradicals in other ways, such as from cyclic diazo precursors, results in formation of both alkenes and cyclobutanes, with stereochemical details consistent with kinetically competitive bond rotations before the diradical gives cyclobutanes or alkenes. From the tetraalkyl-substituted systems (5) and (6), cyclobutane products are formed with very high retention stereospecificity,while the diradicals generated from the azo precursors (7) and (8) lead to alkene and cyclobutane products with some loss of stereochemical definition. ... 

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