Generation and Synthetic Application of Metallated Methyl Isopropenyl Ether, A Substitute for Acetone Enolate
作者:Foroogh Taherirastgar、Lambert Brandsma
DOI:10.1002/cber.19971300107
日期:1997.1
Methylisopropenylether (1) has been metallated at low temperature with a 1:1 molar mixture of n-BuLi/t-BuOK in THF-hexane, and subsequently functionalized with a variety of electrophilic reagents. At temperatures higher than – 30°C, the metallatedmethylisopropenylether (2) decomposes with formation of allene. When the suspension of 2 is allowed to warm up to room temperature in the presence of
甲基异丙烯基醚(1)已在低温下以1:1摩尔n -BuLi / t -BuOK在THF-己烷中的混合物进行了金属化处理,随后用各种亲电试剂进行了功能化。在高于– 30°C的温度下,金属化的甲基异丙烯基醚(2)分解并形成丙二烯。当在额外的当量正丁基锂存在下让2的悬浮液升温至室温时,中间的丙二烯转化为1-丙炔基锂(2c),后者与硫氰酸丙酯反应生成1-丙硫基-1-丙炔(4)。对某些官能化产物进行酸性水解,得到预期的甲基酮。
作者:Alexey Yu. Dubovtsev、Dmitry V. Dar'in、Vadim Yu. Kukushkin
DOI:10.1002/adsc.201900097
日期:2019.6.18
Three‐component [2+2+1] gold(I)‐catalyzed reaction of internalalkynes (alkynyl esters or ‐ketones), nitriles, and 2‐chloropyridine N‐oxide led to a wide range of fully substituted 1,3‐oxazoles (32 examples; up to 92% isolated yields). Nitrile R3CN species, employed in the reaction as both reactants and solvents, comprise conventional nitriles (R3=Alk, Ar) and also push‐pull systems such as cyanamides
An experimental and theoretical study of the dimetallation of vinylacetylene
作者:Lambert Brandsma、Hendrik Hommes、Hermann D. Verkruijsse、Alexander J. Kos、Wolfgang Neugebauer、Wolfgang Baumgärtner、Paul von Ragué Schleyer
DOI:10.1002/recl.19881070334
日期:——
when butyllithium is used alone or in the presence of TMEDA. Supporting experimental and calculational (ab initio and MNDO) results suggest that the potassium acetylide, KC≡C-CH = CH2, is formed first. Further metallation occurs at the activated C-2 vinyl position. Preferential substitution at the C-2 position in t-BuC≡CCH = CHt-Bu also was demonstrated. Neither dianion nor dilithium models account for
18-crown-6-ether or more conveniently using lead thiocyanate. The phosphonium salt 8 and phosphoranes 9 were employed as convenient novelreagents for convertinghydroxygroups into thiocyanate and isothiocyanatefunctions with high stereoselectivity under very mild conditions. The efficient synthesis of acylisothiocyanales RCONCS, R2P(O)NCS and R2P(S)NCS via addition of thiocyanogen to mixed anhydrides is
已通过31 P NMR光谱研究了硫氰酸盐在三苯基膦中的氧化加成反应,表明形成了异硫氰酸根合salt盐8。硫氰酸根与烷基邻亚苯基亚磷酸酯7之间的类似反应导致生成二异硫氰酸根合膦酸酯9。在18-冠-6-醚的存在下,或更优选地使用硫氰酸铅,通过硫氰酸钾的作用,通过相应的氯salt盐12和烷基二氯-邻亚苯基亚膦酸酯13的配体取代,制备了相同的产物。salt盐8和膦烷9在非常温和的条件下,将其用作方便的新颖试剂,用于将羟基基团转化为具有高立体选择性的硫氰酸酯和异硫氰酸酯官能团。通过将硫氰酸根加到混合酸酐中来有效合成酰基异硫氰酸酯RCONCS,R 2 P(O)NCS和R 2 P(S)NCS。