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Orthogonal protection is a strategy allowing the specific deprotection of one protective group in a multiply-protected structure. For example, the amino acid tyrosine could be protected as a benzyl ester on the carboxyl group, a fluorenylmethylenoxy carbamate on the amine group, and a tert-butyl ether on the phenol
This is a list of some of the more commonly known problems that are NP-complete when expressed as decision problems. As there are thousands of such problems known, this list is in no way comprehensive. Many problems of this type can be found in Garey & Johnson (1979).
For example, (C 6 H 5)(CH 3) 2 C + is referred to as a "benzylic" carbocation. The benzyl free radical has the formula C 6 H 5 CH 2 • . The benzyl cation or phenylcarbenium ion is the carbocation with formula C 6 H 5 CH + 2 ; the benzyl anion or phenylmethanide ion is the carbanion with the formula C 6 H 5 CH − 2 .
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In computational complexity theory, Karp's 21 NP-complete problems are a set of computational problems which are NP-complete.In his 1972 paper, "Reducibility Among Combinatorial Problems", [1] Richard Karp used Stephen Cook's 1971 theorem that the boolean satisfiability problem is NP-complete [2] (also called the Cook-Levin theorem) to show that there is a polynomial time many-one reduction ...
Benzyl chloroformate is commonly used in organic synthesis for the introduction of the benzyloxycarbonyl (formerly called carboxybenzyl) protecting group for amines.The protecting group is abbreviated Cbz or Z (in honor of discoverer Zervas), hence the alternative shorthand designation for benzyl chloroformate as Cbz-Cl or Z-Cl.
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Trimethylsilylacetylene is also used to synthesize diphenylacetylene derivatives in a one-pot Sonogashira coupling, in which the phenylacetylene derivative reacts with a second aryl halide after in-situ deprotection. [3] A less expensive alternative reagent is 2-methylbut-3-yn-2-ol, which after alkynylation is deprotected with base.