Structure butyl-derivative synthesis

Phosphorinane, 4-t-butyl-1 -phenyl-synthesis, 1, 500 Phosphorinane, I-chloro-synthesis, 1, 500 Phosphorinane, 1-hydrocarbyl-I-sulfide synthesis, 1, 500 Phosphorinane, 1-phenyl-synthesis, 1, 499 Phosphorinanes, 1, 497-506 bicyclic bridged derivatives synthesis, 1, 501 conformation, 1, 503-504 NMR, 1, 497 oxidation, 1, 498 reactions, 1, 497 structure, 1, 497, 503-504 sulfuration, 1, 499 synthesis, 1, 499... 

Friedel-Crafts alkylation of 2,5-dimethylthiophene with f-butyl chloride and A1C13 gave only the mono-r-butylated product (49) and none of the expected di-f-butylated thiophene (50). In order to facilitate di-r-butylation at positions 3 and 4, the substituents at 2 and 5 were tied back in the thiophenophane (51). This on alkylation gave, unexpectedly, the rearranged mono-f-butyl derivatives (52 30%) and (53 57%), and the di-f-butyl derivative (54 12%). The structures of the products were proved by NMR, Raney nickel desulfurization and independent synthesis (75T2551). One other such isomerization under Friedel-Crafts conditions had been previously reported (65JOC1058) 2,5-di-f-butylthiophene isomerizing to 2,4-di-f-butylthiophene. 

Both saturated (50) and unsaturated derivatives (51) are easily accepted by lipases and esterases. Lipase P from Amano resolves azide (52) or naphthyl (53) derivatives with good yields and excellent selectivity. PPL-catalyzed resolution of glycidyl esters (54) is of great synthetic utility because it provides an alternative to the Sharpless epoxidation route for the synthesis of (3-blockers. The optical purity of glycidyl esters strongly depends on the structure of the acyl moiety the hydrolysis of propyl and butyl derivatives of epoxy alcohols results in esters with ee > 95% (30). 

Despite the highly unusual structure of tetrahedrane, 3, the problem of its synthesis had been formulated more than 70 years ago (96). The first review article on tetrahedrane (97) appeared almost simultaneously with the paper describing the first synthesis of its tetra-t-butyl derivative 77 (5), which, until recently (98), remained the only tetrahedrane derivative known. On the basis of MM calculations using different force fields Hounshell and Mislow predicted T symmetry for 77 (99). Minkin etal. (17c) discussed the synthesis, reactions, and stability of 3 and 77 pointing out that high kinetic stability of the latter molecule is partly due to unfavorable steric repulsions in the... 

The squarylium (4.6) and croconium (4.7) dyes are closely related structurally to cyanines but are in fact donor-acceptor molecules and consequently the design principles of near-IR absorbers based on these chromophores are different. The synthesis of these chromophores is achieved easily by reacting either squaric acid, or preferably an alkylated derivative, e.g. di-n-butyl squarate, or croconic acid with electron-donor molecnles. The croconium dyes absorb at significantly longer wavelengths than the sqnarylinms as shown in Figure 4.2. 

Here we report the synthesis and catalytic application of a new porous clay heterostructure material derived from synthetic saponite as the layered host. Saponite is a tetrahedrally charged smectite clay wherein the aluminum substitutes for silicon in the tetrahedral sheet of the 2 1 layer lattice structure. In alumina - pillared form saponite is an effective solid acid catalyst [8-10], but its catalytic utility is limited in part by a pore structure in the micropore domain. The PCH form of saponite should be much more accessible for large molecule catalysis. Accordingly, Friedel-Crafts alkylation of bulky 2, 4-di-tert-butylphenol (DBP) (molecular size (A) 9.5x6.1x4.4) with cinnamyl alcohol to produce 6,8-di-tert-butyl-2, 3-dihydro[4H] benzopyran (molecular size (A) 13.5x7.9x 4.9) was used as a probe reaction for SAP-PCH. This large substrate reaction also was selected in part because only mesoporous molecular sieves are known to provide the accessible acid sites for catalysis [11]. Conventional zeolites and pillared clays are poor catalysts for this reaction because the reagents cannot readily access the small micropores. 

Corey, E. J. Rao, K. S. Enantioselective total synthesis of ginkgolide derivatives lacking the tert-butyl group, an essential structural subunit for antagonism of platelet activating factor. Tetrahedron l tt., 1991, 32 4623-4626. 

---