However, I am not sure how much this principle extends to protection of compounds with only two hydroxyl groups. 19.47b and c). The diols can be protected in high yields and released from their corresponding acetals with high chemical efficiency. 19.10 ACETALS AND THEIR USE AS PROTECTING GROUPS 923 The formation of hemiacetals is catalyzed not only by acids but by bases as well (Problem 19.16b, p. 910). Protecting Groups in Organic Synthesis-8 Ready acetal protection of diols Cyclic acetal are wonderful protecting groups for 1,2 and 1,3 diols. Benzylidene-Type Photolabile Diol Protecting Groups, Structurally Simple Benzylidene-Type Photolabile Diol The diols can be protected Two structurally simple photolabile protecting groups for releasing 1,2- and 1,3-diols have been developed. 2014,,, 17-471. DOI: 10.1002/9781118905074.ch02. However, the conversion of hemiacetals into acetals is catalyzed only by acids (Eqs. Scott F. Hickey, Ming C. Hammond. in high yields and released from their corresponding acetals with Two structurally simple photolabile I am guessing it should be possible to protect 1,3-diols with acetone too - after all, a methyl group is hardly the worst axial substituent to have. protecting groups for releasing Protection for the Hydroxyl Group, Including 1,2- and 1,3-Diols. Some of the most common: OOOO 'acetonide' most stable least stable Usually, 1,2 >1,3>1,4 HO OH OH O OH O O O 5: 1 On: … Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Structure-Guided Design of Fluorescent S-Adenosylmethionine Analogs for a High-Throughput Screen to Target SAM-I Riboswitch RNAs. Protecting Groups Hydroxyl Protecting Groups 26 Protection of 1,2 & 1,3-diols 4. p-Methoxybenzylidene acetals: Cleavage: Hydrolyzed about 10 times faster than regular benzylidenes OO R1R2 HOOH R1R2 Acid CH(OMe)2 CHO or OMe OMe OMe Can be oxidatively removed with CAN high chemical efficiency. 1,2- and 1,3-diols have been developed. Any type of content formally published in an academic journal, usually following a peer-review process. Protecting Groups, Environmental Sciences not elsewhere classified, Biological Sciences not elsewhere classified. Chemistry & Biology 2014, 21, 345-356 Protecting Groups: A Necessary Evil 3 Note, however, that each protecting group incorporated in a multi-step synthesis increases the synthesis by two non-productive steps reducing the overall yield and efficiency of the synthesis.