Criticism
In a 2007 paper Phil Baran notes that even though the textbooks state that the use of protective groups is unavoidable and that they are ideally easily added and removed, in practical terms in organic synthesis their use adds two synthetic steps (protection-deprotection sequence) to a chemical sequence and sometimes dramatically lowers chemical yield. Crucially, added complexity impedes the use of synthetic total synthesis in drug discovery. In contrast biomimetic synthesis does not employ protective groups. As an alternative, Baran presented a novel protective-group free synthesis of the compound hapalindole U. The previously published synthesis according to Baran, contained 20 steps with multiple protective group manipulations (two confirmed):
| Hapalindole U Baran 2007 protective-group free | Hapalindole U Muratake 1990 Ts protective groups in blue |
Read more about this topic: Protecting Groups
Famous quotes containing the word criticism:
“I, with other Americans, have perhaps unduly resented the stream of criticism of American life ... more particularly have I resented the sneers at Main Street. For I have known that in the cottages that lay behind the street rested the strength of our national character.”
—Herbert Hoover (1874–1964)
“Cubism had been an analysis of the object and an attempt to put it before us in its totality; both as analysis and as synthesis, it was a criticism of appearance. Surrealism transmuted the object, and suddenly a canvas became an apparition: a new figuration, a real transfiguration.”
—Octavio Paz (b. 1914)
“...I wasn’t at all prepared for the avalanche of criticism that overwhelmed me. You would have thought I had murdered someone, and perhaps I had, but only to give her successor a chance to live. It was a very sad business indeed to be made to feel that my success depended solely, or at least in large part, on a head of hair.”
—Mary Pickford (1893–1979)