The major product formed in the following reaction is
Epoxides fused to a pyranose ring are opened by nucleophiles in an SN2 fashion with trans-diaxial geometry (Fürst–Plattner rule), and the regioselectivity in 2,3-anhydro sugars is strongly biased: attack at C-2, next to the anomeric carbon, is disfavoured because the electronegative ring oxygen and the anomeric OCH3 destabilise the SN2 transition state there.
Step 1 — The higher-order cyanocuprate Me2Cu(CN)Li2 delivers a methyl group to C-3, anti to the epoxide oxygen. The methyl ends up on the face opposite to the former epoxide (hashed), and the oxygen stays on C-2 as a free hydroxyl (wedged), trans to the new methyl.
Step 2 — TBAF cleaves the TBDMS ether and frees the primary CH2OH.
Structures that keep the CH2OTBDMS group overlook the fluoride deprotection, and those with the methyl at C-2 and the hydroxyl at C-3 correspond to the disfavoured attack next to the anomeric centre.
the 3-C-methyl pyranoside with a free 2-OH and CH2OH group option is correct.
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Important Questions from Mixed Topic (MH-SET)
.................... is a client server application that identifies each host on the internet with a unique user-friendly name.
Every OS has a ................ or .......... which primarily resides in the main memory of the computer to perform some of the basic functions of the OS.
(i) Kernel
(ii) Interface
(iii) Nucleus
(iv) Compiler
Codes:
Which of the following are referred to as low level language?
(i) Machine language
(ii) Assembly language
(iii) High level language
(iv) Natural language
Codes:
Match the following:
List I List II (a) New York Public Library (i) Shelv AR (b) Miami University Augmented Research Group (ii) Smart library (c) Oula University Library (iii) Wolf Walk (d) North Carolina State University (iv) Find the future Codes:
Which part of the QR code represents the encoded data?
