An efficient and simple source of nitroso reagents and their oxidation reactions are described. The combination of a Lewis acid and a metal nitrite was applied to the oxidation of silyl enol ethers. Amino acid and peptide derivatives were easily accessed through in situ C-C bond cleavage of fully substituted silyl enol ethers upon oxidation.
描述了亚硝基试剂及其氧化反应的有效且简单的来源。路易斯酸和金属亚硝酸盐的组合应用于甲硅烷基烯醇醚的氧化。通过氧化时完全取代的甲硅烷基烯醇醚的原位 CC 键裂解,可以很容易地获得氨基酸和肽衍生物。
β-Siloxy-α-haloketones through Highly Diastereoselective Single and Double Mukaiyama Aldol Reactions
作者:Jakub Saadi、Hisashi Yamamoto
DOI:10.1002/chem.201204493
日期:2013.3.18
Double‐action haloketones: A super silyl group enabled the first highlydiastereoselectiveMukaiyamaaldolreactions of α‐chloro‐ and α‐fluoroketones with a wide range of aldehydes, providing anti‐β‐siloxy‐α‐haloketones. This process is compatible with one‐pot double‐aldol methodology and allows for rapid access to new halogen‐modified polyketide fragments bearing up to four contiguous stereocenters
Remarkable Tris(trimethylsilyl)silyl Group for Diastereoselective [2 + 2] Cyclizations
作者:Matthew B. Boxer、Hisashi Yamamoto
DOI:10.1021/ol0512334
日期:2005.7.1
[reaction: see text] Diastereoselective [2 + 2] cyclizations of aldehyde- and ketone-derived silyl enol ethers with acrylates is described. The use of the tris(trimethylsilyl)silyl group allows for unprecedented reactivity, yields, and selectivity for these cyclizations. The presence of silicon-silicon bonds proved to be important for this transformation, where typical silyl groups (TBS and TIPS) failed
Stereodivergent Approach to the Avermectins Based on “Super Silyl” Directed Aldol Reactions
作者:Patrick B. Brady、Susumu Oda、Hisashi Yamamoto
DOI:10.1021/ol501327g
日期:2014.8.1
A stereodivergent approach to the spiroketal fragment of the avermectins is described. The strategy utilizes a sequence of three aldol reactions directed by the tris(trimethylsilyl)silyl “super silyl” group. Central to this strategy is that each aldol reaction can be controlled to allow access to either diastereomer in high stereoselectivity, thereby affording 16 stereoisomers along the same linear
The use of the tris(trimethylsilyl)silyl (TTMSS) group in aldehyde-derived silyl enol ethers affords aldehyde cross-aldol products with high yields and allows for unprecedented reactivity. The reaction is catalyzed by 0.05 mol % of HNTf2, and can easily be managed to give beta,delta-bis-, beta,delta,gamma-tris-, and beta,delta,zeta-tris-hydroxy-aldehydes with extremely high selectivity by simple stoichiometric control. High diastereoselectivity is obtained in all cases, and the use of chiral aldehydes affords Felkin products when there are nonchelating substituents, chelation products when there is a chelating sbustituent, and syn products when there is beta-substitution. HNTf2 is proposed to be an initiator, and highly Lewis acidic TTMSSNTf2 is the true catalyst.