Trans-complementation

Further improvements to vims expression systems include trans-complementation of some of the virus functions from transgenic host plants (P12 plants for AlMV). By integrating parts of the viral vector into the plant chromosome, this system has the potential for multiple technical solutions that could overcome limitations of classical viral vectors [33]. Viral vectors can be used as molecular switches for tightly controlled, high-level transgene expression (Hull et al. unpublished data). 

Le Grice, S. F., Mills, J., and Mous, J.(1988). Active site mutagenesis of the AIDS virus protease and its alleviation by trans complementation. EMBO J. 7,2547-2553. 

Bianchi, A.A. and McGrew, J.T. (2003) High-level expression of full-length antibodies using trans-complementing expression vectors. Bio-technol. Bioeng. 84 439-444. 

Bartoli recently discovered that by switching from azide to p-anisidine as nucleophile, the ARO of racemic trans- 3-substituted styrene oxides could be catalyzed by the (salen)Cr-Cl complex 2 with complete regioselectivity and moderate selectivity factors (Scheme 7.36) [14]. The ability to access anti-P-amino alcohols nicely complements the existing methods for the preparation of syn-aryl isoserines and related compounds [67] by asymmetric oxidation of trans-cinnamate derivatives [68]. 

Coeffet-Le Gal, M.F., Thurston, L., Rich, P. et al. (2006) Complementation of daptomycin dpt A and dptD deletion mutations in trans and production of hybrid lipopeptide antibiotics. Microbiology (Reading, England), 152,2993. 

The only other alkenyl carbenoid with a proton trans to the halide that can readily be generated by deprotonation is the parent 1-lithio-l-chloroethene 57 [43] (Scheme 3.13). Insertion into organozirconocenes arising from hydrozirconation of alkenes and alkynes, followed by protonation, affords terminal alkenes and ( )-dienes 59, respectively [38]. The latter provides a useful complement to the synthesis of 54 in Scheme 3.12 since the stereocontrol is >99%. 

This experimental procedure in section 6.5.7 can be used to epoxidize certain cyclic as well as acychc cw-olefins with good enantioselectivity and no cis/trans-isomerization (Table 6.7). Promising results have also been observed for some terminal olefins with this new glucose-derived catalyst, which complements our previously reported trans- and trisubstituted olefin catalyst 1. 

Recently, we [53] and others [54] simultaneously reported an example of a complex in which the transition metal dictates the coordination mode, viz. urea-functionalized phosphine 20, which forms a trans palladium complex, complemented by hydrogen bonding ofthe urea fragments (Figure 10.6). Bear in mind that any monophosphine, and even wide bite angle diphosphines, give trans complexes with a hydrocarbyl palladium halide. More interestingly, the urea moieties can function as a host for another halide ion. 

The cycloaddition of some nitrile oxides to trans-1,2-disubstituted alkenebor-onates afforded the respective isoxazoline-4-boronates with high regioselectivity. These products were then used to prepare the 4-hydroxy derivatives (139) complementing earlier approaches that took advantage of 4-modification (140,141) of furan cycloaddition products (20,21) (see Section 6.4.4). 

The formation of a bromohydrin via the addition of hyprobromous acid to olefins complements the above mentioned route. This reagent adds to the double bond in a trans-diaxial manner, the addition being initiated by the attack of a positive bromonium ion from the less hindered side. The... 

Reactions of acyclic derivatives with carbon electrophiles have also been examined.33,34 An illustrative reaction involving methylation of the unsubstituted complex [MnCr 4-butadiene)(CO)3], (19), is shown in Scheme 16. Again, the reaction is presumed to occur via a methylmanganese species (20) and after methyl migration the unsaturated metal center is stabilized by formation of a Mn—H—C bridge (isomers 21a and 21b). Deprotonation of equilibrating (21a and 21b) yields the [Mn(l-methylbutadiene)(CO>3]-complex (22), which has exclusively trans stereochemistry.34 This sequence represents alkylation of the terminal carbon of butadiene and complements the iron carbonyl chemistry, where terminal acylation has been achieved as described above. Unpublished results indicate that a second methylation of (22) occurs... 

RW Le Page, MP Barrett. Cloning of the 6-phosphoglucanate dehydrogenase gene from Trypanosoma brucei by complementation in Escherichia coli. Biochem Soc Trans 18 724-727, 1990. 

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